SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5535f73205d71eeb597445889b4564327b27353cb0ed184068d341c1fa53883' 
  AND token = 'PQTrhTeyGlTgHjYKGkDf4+RUquOfcb5m737pom44OSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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