Been doing this for a couple of years. The feature is built into my main belt-drive double car garage door opener (Chamberlain) and I've installed the myQ unit on the old single car chain-drive unit. My Q is the tits, and Amazon's compliance with the Key delivery feature is pretty high.
The myQ units are routinely on sale for under $30, so this isn't a huge investment and it also gives you the ability to remotely open and close your garage doors. I also have mine set to automatically close (if they're open) at 10 p.m. so I don't inadvertently leave them open at night. Absolute no brainer of an investment and installation.