diff --git a/README.md b/README.md
index b6a44d14..d0b708cc 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,7 @@ These steps help you install Python via pyenv and Poetry. If you already have Po
 
 ```bash
 # on ubuntu:
-sudo apt install -y build-essential pkg-config libffi-dev libpq-dev zlib1g-dev libssl-dev python3-dev libsqlite3-dev ncurses-dev libbz2-dev libreadline-dev lzma-dev
+sudo apt install -y build-essential pkg-config libffi-dev libpq-dev zlib1g-dev libssl-dev python3-dev libsqlite3-dev ncurses-dev libbz2-dev libreadline-dev lzma-dev liblzma-dev
 
 # install python using pyenv
 curl https://pyenv.run | bash
diff --git a/cashu/mint/crud.py b/cashu/mint/crud.py
index cf376e28..0ef4af9d 100644
--- a/cashu/mint/crud.py
+++ b/cashu/mint/crud.py
@@ -36,23 +36,15 @@ async def get_keyset(
         ...
 
     @abstractmethod
-    async def get_spent_proofs(
+    async def get_proofs_used(
         self,
         *,
+        Ys: List[str],
         db: Database,
         conn: Optional[Connection] = None,
     ) -> List[Proof]:
         ...
 
-    async def get_proof_used(
-        self,
-        *,
-        Y: str,
-        db: Database,
-        conn: Optional[Connection] = None,
-    ) -> Optional[Proof]:
-        ...
-
     @abstractmethod
     async def invalidate_proof(
         self,
@@ -157,6 +149,16 @@ async def get_promise(
     ) -> Optional[BlindedSignature]:
         ...
 
+    @abstractmethod
+    async def get_promises(
+        self,
+        *,
+        db: Database,
+        b_s: List[str],
+        conn: Optional[Connection] = None,
+    ) -> List[BlindedSignature]:
+        ...
+
     @abstractmethod
     async def store_mint_quote(
         self,
@@ -294,18 +296,21 @@ async def get_promise(
         )
         return BlindedSignature.from_row(row) if row else None
 
-    async def get_spent_proofs(
+    async def get_promises(
         self,
         *,
         db: Database,
+        b_s: List[str],
         conn: Optional[Connection] = None,
-    ) -> List[Proof]:
+    ) -> List[BlindedSignature]:
         rows = await (conn or db).fetchall(
             f"""
-            SELECT * from {db.table_with_schema('proofs_used')}
-            """
+            SELECT * from {db.table_with_schema('promises')}
+            WHERE b_ IN ({','.join([':b_' + str(i) for i in range(len(b_s))])})
+            """,
+            {f"b_{i}": b_s[i] for i in range(len(b_s))},
         )
-        return [Proof(**r) for r in rows] if rows else []
+        return [BlindedSignature.from_row(r) for r in rows] if rows else []
 
     async def invalidate_proof(
         self,
@@ -722,18 +727,17 @@ async def get_keyset(
         )
         return [MintKeyset(**row) for row in rows]
 
-    async def get_proof_used(
+    async def get_proofs_used(
         self,
         *,
-        Y: str,
+        Ys: List[str],
         db: Database,
         conn: Optional[Connection] = None,
-    ) -> Optional[Proof]:
-        row = await (conn or db).fetchone(
-            f"""
-            SELECT * from {db.table_with_schema('proofs_used')}
-            WHERE y = :y
-            """,
-            {"y": Y},
-        )
-        return Proof(**row) if row else None
+    ) -> List[Proof]:
+        query = f"""
+        SELECT * from {db.table_with_schema('proofs_used')}
+        WHERE y IN ({','.join([':y_' + str(i) for i in range(len(Ys))])})
+        """
+        values = {f"y_{i}": Ys[i] for i in range(len(Ys))}
+        rows = await (conn or db).fetchall(query, values)
+        return [Proof(**r) for r in rows] if rows else []
diff --git a/cashu/mint/db/read.py b/cashu/mint/db/read.py
index ac35ec80..681ebe21 100644
--- a/cashu/mint/db/read.py
+++ b/cashu/mint/db/read.py
@@ -35,10 +35,8 @@ async def _get_proofs_spent(
         proofs_spent_dict: Dict[str, Proof] = {}
         # check used secrets in database
         async with self.db.get_connection(conn) as conn:
-            for Y in Ys:
-                spent_proof = await self.crud.get_proof_used(db=self.db, Y=Y, conn=conn)
-                if spent_proof:
-                    proofs_spent_dict[Y] = spent_proof
+            spent_proofs = await self.crud.get_proofs_used(db=self.db, Ys=Ys, conn=conn)
+        proofs_spent_dict = {p.Y: p for p in spent_proofs}
         return proofs_spent_dict
 
     async def get_proofs_states(
diff --git a/cashu/mint/protocols.py b/cashu/mint/protocols.py
index ff576d96..0e84ea3a 100644
--- a/cashu/mint/protocols.py
+++ b/cashu/mint/protocols.py
@@ -4,6 +4,8 @@
 from ..core.db import Database
 from ..lightning.base import LightningBackend
 from ..mint.crud import LedgerCrud
+from .db.read import DbReadHelper
+from .db.write import DbWriteHelper
 from .events.events import LedgerEventManager
 
 
@@ -18,6 +20,8 @@ class SupportsBackends(Protocol):
 
 class SupportsDb(Protocol):
     db: Database
+    db_read: DbReadHelper
+    db_write: DbWriteHelper
     crud: LedgerCrud
 
 
diff --git a/cashu/mint/verification.py b/cashu/mint/verification.py
index f0ce828c..ae2c5725 100644
--- a/cashu/mint/verification.py
+++ b/cashu/mint/verification.py
@@ -25,6 +25,8 @@
 from ..lightning.base import LightningBackend
 from ..mint.crud import LedgerCrud
 from .conditions import LedgerSpendingConditions
+from .db.read import DbReadHelper
+from .db.write import DbWriteHelper
 from .protocols import SupportsBackends, SupportsDb, SupportsKeysets
 
 
@@ -37,6 +39,8 @@ class LedgerVerification(
     keysets: Dict[str, MintKeyset]
     crud: LedgerCrud
     db: Database
+    db_read: DbReadHelper
+    db_write: DbWriteHelper
     lightning: Dict[Unit, LightningBackend]
 
     async def verify_inputs_and_outputs(
@@ -64,7 +68,10 @@ async def verify_inputs_and_outputs(
         if not proofs:
             raise TransactionError("no proofs provided.")
         # Verify proofs are spendable
-        if not len(await self._get_proofs_spent([p.Y for p in proofs], conn)) == 0:
+        if (
+            not len(await self.db_read._get_proofs_spent([p.Y for p in proofs], conn))
+            == 0
+        ):
             raise TokenAlreadySpentError()
         # Verify amounts of inputs
         if not all([self._verify_amount(p.amount) for p in proofs]):
@@ -156,29 +163,11 @@ async def _check_outputs_issued_before(
         Returns:
             result (List[bool]): Whether outputs are already present in the database.
         """
-        result = []
         async with self.db.get_connection(conn) as conn:
-            for output in outputs:
-                promise = await self.crud.get_promise(
-                    b_=output.B_, db=self.db, conn=conn
-                )
-                result.append(False if promise is None else True)
-        return result
-
-    async def _get_proofs_spent(
-        self, Ys: List[str], conn: Optional[Connection] = None
-    ) -> Dict[str, Proof]:
-        """Returns a dictionary of all proofs that are spent.
-        The key is the Y=h2c(secret) and the value is the proof.
-        """
-        proofs_spent_dict: Dict[str, Proof] = {}
-        # check used secrets in database
-        async with self.db.get_connection(conn=conn) as conn:
-            for Y in Ys:
-                spent_proof = await self.crud.get_proof_used(db=self.db, Y=Y, conn=conn)
-                if spent_proof:
-                    proofs_spent_dict[Y] = spent_proof
-        return proofs_spent_dict
+            promises = await self.crud.get_promises(
+                b_s=[output.B_ for output in outputs], db=self.db, conn=conn
+            )
+        return [True if promise else False for promise in promises]
 
     def _verify_secret_criteria(self, proof: Proof) -> Literal[True]:
         """Verifies that a secret is present and is not too long (DOS prevention)."""