I have a layover of more than 6 hours in Lima, what can I do?

I will be travelling to Uruguay in December, on my way there I will spend a night in El Salvador and about 6 hours in Lima Peru. What can I visit not too far from Chavez airport? I have 2 kids and one is only 3 and a half so a lot of walking will not do. I wish I could go to Machu Pichu but I'm pretty sure it's out of question.