Preheat the oven to 350°F and line an 8×8-inch baking dish with parchment paper.
Combine the graham cracker crumbs, sugar, and melted butter in a medium-sized mixing bowl. Stir until the mixture resembles wet sand.
Firmly press the crumb mixture into the base of the prepared pan, forming an even layer. Bake the crust for 5 minutes.
In the same bowl, whisk together the sweetened condensed milk, lemon juice, and egg yolks until the mixture is thoroughly blended.
Pour the lemon filling evenly over the baked crust.
Return the pan to the oven and bake for an additional 15 to 20 minutes, or until the lemon layer is set and firm to the touch.
Allow the bars to cool entirely in the pan before slicing into squares.