SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1dd76f39ea633b3727be299db74e430a816218800c8d9b13198b713fd31454be' 
  AND token = 'MUkQARkuKgBOhNFlrxnD5TeYdBjrH9X+u0KVOIZclP0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}