Apple will fix it for free!
'''Keyboard Service Program for MacBook, MacBook Air, and MacBook Pro'''
Apple has determined that a small percentage of the keyboards in certain MacBook, MacBook Air, and MacBook Pro models may exhibit one or more of the following behaviors:
* Letters or characters repeat unexpectedly
* Letters or characters do not appear
* Key(s) feel "sticky" or do not respond in a consistent manner
Apple or an Apple Authorized Service Provider will service eligible MacBook, MacBook Air, and MacBook Pro keyboards, free of charge. The type of service will be determined after the keyboard is examined and may involve the replacement of one or more keys or the whole keyboard.
https://support.apple.com/keyboard-service-program-for-mac-notebooks