whats the best way to clean a magic keyboard

See the following from How to clean your Apple products - Apple Support

Apple wireless or USB keyboards, mice, and trackpads

First, power off the device. If your device uses removable batteries, remove the batteries. (If your device is wired, simply unplug it from your computer.)

Next, clean the outside of your device with a lint-free cloth lightly moistened with water. Don't get moisture in any openings or use aerosol sprays, solvents, abrasives, or cleaners containing hydrogen peroxide.

If your Magic Mouse or Magic Mouse 2 isn’t tracking properly, there might be a hair or other debris on the sensor lens. Turn the mouse over and inspect the sensor window using a bright light. If you see debris, use compressed air to gently clean the sensor window.