1. To make crust: Heat oven to 450°. Combine graham cracker crumbs with sugar and salt. Evenly spread 2 tablespoons crumb mixture on a clean work surface. Unroll pie crust over top of crumbs. Evenly sprinkle top of dough with an additional 2 tablespoons crumbs. Use a rolling pin to lightly press crumbs into pie dough. Flip dough and repeat process of sprinkling 2 tablespoons of crumbs and pressing them in 1 more time.
2. Firmly press pie dough into pie plate, folding access under to create a thick edge. Flute edge and prick crust all over bottom and sides with a fork. Bake for 10 minutes. Remove from oven and let cool to room temperature while preparing filling. Reduce oven temperature to 350°.
3. To make filling: Using an electric mixer, combine cream cheese, egg yolks, lime zest, and sea salt until smooth. Add sweetened condensed milk and mix until no lumps of cream cheese remain, scraping bowl as needed. Add lime juice and mix on low until incorporated.
4. Transfer filling to prepared pie crust and smooth top. Bake until set, about 12 minutes. Meanwhile, make meringue so it is ready to place on top of baked filling as soon as it is removed from the oven.
5. To make meringue: Using an electric mixer, beat egg whites and salt on medium-low speed until foamy. Add cream of tartar and increase speed to high. Beat until soft peaks form. Gradually add sugar and continue to beat until stiff, shiny peaks form.
6. Decoratively spoon meringue over hot-from-the-oven pie, making sure to connect meringue to edge of pie crust to prevent shrinkage. Bake until meringue is lightly browned, about 15 minutes. Let cool to room temperature before serving.
7. Combine 1 teaspoon finely grated lime zest with 1 teaspoon sugar in a small bowl. Garnish top of pie with lime-sugar mixture before serving.
NOTE: I prefer using a pre-made pie dough to reduce the steps in preparing this recipe. However, if you prefer to use a freshly made dough, simply roll the dough out onto the crumbs and proceed with recipe. Key limes are considerably more tart and bitter than the regular grocery store variety of limes (typically Persian). But either juice works well in this recipe.