SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7c320bd46afc4f60b9164b9312356d66853492cbc97a240c4310e9015e7d428' 
  AND token = '6aYsI/Gyj3K794KpyC4W82EznOcLcOKNEozMroRJ2nk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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