As far as I am aware, you cannot purchase access to the excellent Iberia lounges which is part of the reason that they do still feel like "VIP" lounges. These are reserved for passengers flying in Business or with status. There may be other lounges where access can be purchased. See this
http://www.aena.es/csee/Satellite/Ae...P-Lounges.html
Never seen a Carl's Jr in Spain, I'm afraid!