Preheat oven to 350 degrees F (175 degrees C). Line muffin cups with paper liners.
Mix flour, salt, nutmeg, baking soda, and baking powder in a mixing bowl.
Beat egg, sugar, and vegetable oil together in a large bowl. Fold zucchini and raisins into egg mixture until evenly mixed. Stir flour mixture into the wet mixture to make a batter. Divide batter into 12 muffin cups to about 2/3 full.
Bake in the preheated oven until golden and the tops spring back when lightly pressed, about 25 minutes.