Adjust oven rack to middle position and heat oven to 375 degrees. Line 2 12-cup muffin tins with paper liners and coat with nonstick spray.
In a large bowl, whisk together flour, 1 cup sugar, poppy seeds, baking powder, baking soda, and salt.
In a second bowl, whisk together yogurt, eggs, and lemon zest. Fold yogurt mixture into flour mixture with a rubber spatula until just combined. Carefully fold in melted butter.
Using a greased 1/3-cup dry measuring cup, divide batter evenly among prepared muffin cups. Bake until the tops are golden brown and a toothpick inserted in the center of a muffin comes out clean with a few crumbs attached, about 25 to 30 minutes. Rotate muffin tin halfway through.
Let muffins cool in muffin tin for 5 minutes, then turn out onto a wire rack and brush with glaze (instructions follow).