SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81fece4d2b4be5eb19a506f617481951aaeb6b516cc13bc49ab8bd8125a42fda' 
  AND token = '3qFpDQ5zRE6fkyt+XToShK/HKcP7EAmIsgQ9HzpsWE4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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