SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c31a86350159c38f710954f9f9442f166c2508dbf0fa6dd22d55cd878465813' 
  AND token = 'gEEKYtEmviv5zJ7JlAJ5z9jVJ3iaVVx+/KHymJcS7YI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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