SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c6711df1e57bcc16a20187deb685a328a700d93b4f7c823455da9779b932d65' 
  AND token = 'UdoahJDP8dcEIcVAzueIqU7NWhFUoRCYGb60yjpfHwE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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