I had presumed that you had used the generally "tried and true" method of simply popping the key off (yes, it will pop off) and wiped the small area clean with a moistened cloth including the bottom side of the key itself. Compressed air will not remove sticky substances such as coffee, cola, or other beverages

Keys pop off easily using a flat blade such as the tip of a table knife, or a screw driver. Once clean and dry, the key will pop back in with very minimal pressure.

Jim.