SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd48c3193b076480eca2d86fa52f0c692fa7d21296a415d787188676cea85a594' 
  AND token = '8dqKumQSN7I95HxmXq/ZLhw1LdGEBuT/o8Gh7qwqKL0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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