Remove sand from keyboard?

I'm very often outside on the radio with my laptop. I then always sit on a playground, which unfortunately also has a sandpit. Now it happened that a small child sprinkled some sand over part of my keyboard. Everything is still working, but how do I get it out of there. I have already tried to remove the buttons, but somehow does not work. Do you have any advice

If the buttons are tight enough, vacuum cleaners take off at low setting