SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94fdc6ad544e307f1fbcbe4338cbf604b44d993a577e7ed35bc52f48f94dcd4d' 
  AND token = 'v+sTPOuoAiWkl5UwaLuwWYd9Zlv3MyndJddehlSGY1M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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