SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c3348cdda6041660936139dc5f5d9e48b0454150f53146db67c490955005614' 
  AND token = '8y09rALkowJTunFeXHn/QujVDpiLzAVCbV8T9dadViU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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