SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0188e1b5ceba03bb46b811c08ab11db0398be2595575bbe88005cef3da46a9c7' 
  AND token = 'JGiZA1YkzFRpMAbOXhejt0aHY441Hm+DMDJndBLAQXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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