Preheat the oven to 350 degrees F.
For the crust: Crush the graham crackers in a food processor or a resealable plastic bag. Pour them into a bowl and stir in the melted butter and sugar. Press the mixture into a pie pan and bake until golden and set, about 5 minutes. Set aside to cool slightly.
For the filling: Mix the condensed milk, lime zest, lime juice and egg yolks in the bowl of a mixer and mix on high until smooth and thick.
Pour the mixture into the crust and bake for 15 minutes. Allow to cool, then refrigerate for at least 1 hour -- more if possible.
Serve with whipped cream.