diff --git a/sqlite3/db.py b/sqlite3/db.py
index ecf1d89..ab7e0b8 100644
--- a/sqlite3/db.py
+++ b/sqlite3/db.py
@@ -49,4 +49,13 @@ class DB(sqlite3.Connection):
             ''', (pattern,)).fetchall()
         return [row[0] for row in result]
 
-    def __repr__(self): return repr(self.keys())
\ No newline at end of file
+    def __repr__(self): return repr(self.keys())
+
+    def exists(self, key):
+        with self:
+            cur = self.execute('''
+                SELECT 1 FROM kv_store
+                WHERE key = ?
+                LIMIT 1
+            ''', (key,))
+            return bool(cur.fetchone())
\ No newline at end of file