Preheat oven to 350 degrees Fahrenheit.
Mix gluten-free graham cracker crumbs, sugar, and melted butter in a bowl until well combined.
Press crumb mixture into a 9-inch pie plate to form a crust and bake for 10 minutes until set.
In a separate bowl, whisk together sweetened condensed milk, sour cream, egg yolks, and lime zest.
Gradually whisk in the key lime juice until the mixture is thick and uniform.
Pour filling into the pre-baked crust and bake for 15 minutes until the center jiggles slightly but the edges are set.
Cool the pie to room temperature on a wire rack.
Refrigerate for a minimum of 4 hours before slicing and serving.