My right arrow key has not functioned for 6 months. My device is MacBook Air (11-inch, Mid 2012). I have read the article of https://support.apple.com/en-us/HT203162, and it does not solve my issue.
I find so many users have this same problem. It seems to be very weak in key hardware.
MacBook Air, OS X Yosemite (10.10.5), Key failure