SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a231f7019ea391f1f332a960594cb0c127babedb9fd22d4d6aa9b0a7e8e21f57' 
  AND token = '5y2b+zXEn+OxdwRQfBUXZYgbnrMBzxMvf5VqP/HiQGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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