SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '94caa07bbfbd430fade7b9f43e1d53e17b2e6f47305765d767079cd05749be21' 
  AND token = '73uuFEAXBgEn8geFR/SDfpviVKWK2UCtk8YkLpZj+fI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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