diff --git a/libs/checkpoint-sqlite/langgraph/checkpoint/sqlite/_delta.py b/libs/checkpoint-sqlite/langgraph/checkpoint/sqlite/_delta.py
index a28313bdb..21251c0e0 100644
--- a/libs/checkpoint-sqlite/langgraph/checkpoint/sqlite/_delta.py
+++ b/libs/checkpoint-sqlite/langgraph/checkpoint/sqlite/_delta.py
@@ -36,6 +36,10 @@ from langgraph.checkpoint.base import DeltaChannelHistory, PendingWrite
 # descendant's config makes the chain a loop. `step_walk_with_row` stops on a
 # repeated id; sqlite yields recursive rows lazily, so abandoning the cursor
 # ends the recursion.
+#
+# `CROSS JOIN` pins `ancestors` as the outer loop, so each step is one primary
+# key lookup. With a plain `JOIN` and no `ANALYZE` stats, sqlite can put
+# `checkpoints` outside and scan the whole thread per step.
 DELTA_STAGE1_SQL = (
     "WITH RECURSIVE ancestors(checkpoint_id, parent_checkpoint_id, type, "
     "checkpoint) AS ("
@@ -44,7 +48,7 @@ DELTA_STAGE1_SQL = (
     "WHERE thread_id = ? AND checkpoint_ns = ? AND checkpoint_id = ? "
     "UNION ALL "
     "SELECT c.checkpoint_id, c.parent_checkpoint_id, c.type, c.checkpoint "
-    "FROM checkpoints c JOIN ancestors a "
+    "FROM ancestors a CROSS JOIN checkpoints c "
     "ON c.checkpoint_id = a.parent_checkpoint_id "
     "WHERE c.thread_id = ? AND c.checkpoint_ns = ?"
     ") "
diff --git a/libs/checkpoint-sqlite/tests/test_delta_parent_walk.py b/libs/checkpoint-sqlite/tests/test_delta_parent_walk.py
index bdd513366..849752a5d 100644
--- a/libs/checkpoint-sqlite/tests/test_delta_parent_walk.py
+++ b/libs/checkpoint-sqlite/tests/test_delta_parent_walk.py
@@ -11,6 +11,7 @@ from langgraph.checkpoint.base import (
 )
 
 from langgraph.checkpoint.sqlite import SqliteSaver
+from langgraph.checkpoint.sqlite._delta import DELTA_STAGE1_SQL
 from langgraph.checkpoint.sqlite.aio import AsyncSqliteSaver
 
 CHANNEL = "ch"
@@ -87,3 +88,17 @@ def test_walk_terminates_when_put_makes_the_parent_chain_cycle() -> None:
 
         got = saver.get_delta_channel_history(config=b, channels=[CHANNEL])
         assert got[CHANNEL] == {"writes": []}
+
+
+def test_walk_step_looks_up_the_parent_by_primary_key() -> None:
+    with SqliteSaver.from_conn_string(":memory:") as saver:
+        saver.setup()
+        plan = [
+            row[3]
+            for row in saver.conn.execute(
+                f"EXPLAIN QUERY PLAN {DELTA_STAGE1_SQL}", ("t", "", "id", "t", "")
+            )
+        ]
+    assert any(
+        step.startswith("SEARCH c ") and "checkpoint_id=?" in step for step in plan
+    ), f"recursive step should look up the parent by key, got {plan}"