In a medium mixing bowl, combine the graham cracker crumbs, sugar, and melted unsalted butter until fully moistened. Press this mixture into a 9-inch pie dish. Chill for at least 30 minutes.

In a large mixing bowl, beat softened cream cheese with a hand mixer until smooth, about 1-2 minutes. Slowly add sweetened condensed milk and mix until incorporated. Add key lime juice, lime zest, and vanilla extract, mixing until creamy, approximately 2-3 minutes.

Gently fold in the whipped topping using a spatula, starting with a small amount to lighten the mixture, then gradually incorporate the rest.

Pour the filling into the chilled graham cracker crust, smoothing the surface to eliminate gaps or air pockets.

Cover with plastic wrap and refrigerate for at least 4 hours or overnight until set.

Garnish with whipped cream and lime zest or slices, slice and serve chilled.