SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dfe28f808a682c30da1e0fa4e51ab13267acdd84de907cb65c960cca695c15e' 
  AND token = 'wTUfGhIJPeiv79AkjgYWRYOwBgxXDJwpvv5Wmh1F31Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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