Getting into the grooves
If you’re always at your keyboard then you probably don’t think about it much. Even if you do occasionally wipe over the surface, this doesn’t do anything about the first that creeps in between the keys. If you eat whilst you work then it’ll be even worse.
You could start by sliding a piece of paper between the keys to push out the dirt, or you could give it a more thorough clean. Get a can of compressed air and blow out all the dust, or a (clean) soft ketchup bottle as a handmade alternative.