Preheat oven to 350°F. Grease and flour a 10-inch bundt pan.
In the bowl of a stand mixer, beat sugar and softened butter on medium speed until light and fluffy, about 10 minutes.
Add eggs one at a time, mixing each egg fully into the butter mixture before adding the next.
In a separate bowl, whisk together flour, salt, and baking soda.
Add ⅓ of the flour mixture to the butter mixture and mix on low until just combined.
Pour in half of the buttermilk and mix on low until smooth.
Repeat, alternating remaining flour mixture and buttermilk, ending with the flour mixture.
Stir in lemon extract and lemon zest until evenly combined.
Pour batter into prepared pan and smooth the top.
Reduce oven temperature to 325°F and bake 60 to 75 minutes, or until a toothpick inserted in the center comes out with a few moist crumbs, but no wet batter. Check at 60 minutes to prevent overbaking.
Let cake cool in the pan 10 minutes, then transfer to a wire rack or cake platter to cool completely.