Finely crush graham crackers in a food processor or place them in a Ziploc bag and use a rolling pin to crush them.
Stir graham cracker crumbs and sugar together, then add butter, and mix thoroughly.
Firmly press into a 9-inch pie pan.
Place the crust in the freezer to set up while you make the filling.
To make the filling, whip cream with powdered sugar with an electric mixer until stiff peaks form.
Place the cream cheese, sweetened condensed milk, and key lime juice in a large mixing bowl and beat until smooth.
Fold in the whipped cream.
Remove the crust from the freezer and pour the filling into the crust.
Smooth the pie filling with a spatula.
Refrigerate for at least 4 hours or overnight before serving.