Preheat your oven to 350°F (175°C). Combine graham cracker crumbs, melted butter, and granulated sugar, then press the mixture evenly into a 9-inch pie plate and bake for 8-10 minutes.

In a medium bowl, whisk together the sweetened condensed milk, key lime juice, and egg yolks until smooth and well combined. Pour this filling into the prepared and slightly cooled graham cracker crust.

Bake the pie for 12-15 minutes, or until the center is just set but still slightly wobbly. Let it cool completely on a wire rack, then refrigerate for at least 4 hours before serving, ideally overnight.