SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '926592f594b304159b3fbf8d409d86f11b31f7438b25618e073b5dad91f0bdd9' 
  AND token = 'BC4gnapALwY1qUQcYJ+9PwsQI/DpE+FcxtaIovP/cEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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