SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '11a8b7fc69317650896a156ad32a768f05e954b7c1a99c646c27efea4f713e42' 
  AND token = '1RZR7VJGuzA+DcbCUDjHa9ufxKbiBGM26NS/4Ohpg50=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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