SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '650872b50e7fef97a4f38b25830c639aeffe9713600d6c571e8a9a5abba28427' 
  AND token = '7adn5mL0LNaBYQMmBDY+Iq/uKWk5v4UnsicmcbAHCbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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