SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '65741fd5463104060fc857b5fa1b580a969c8bcbede123cbdec37397599fb754' 
  AND token = '1bGOrcpiwHfp4jrgYo/ldYxWo7pxr+cP5DiRGjVDPy8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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