This song is most likely about their fame:
They became famous, locking themselves up inside fame, and they will never get out of it, therefore the "key" is broken. They see all the powers (the fans, the success, the media), and they just look at each other and know what each of them thinks:
They want the time to pass by, but still stay where they are now, because it's where they want to be.
They know that even though fame can be hard, nothing will be able to tear them down, because they have each other, and most importantly their fans.
This song is most likely about their fame: They became famous, locking themselves up inside fame, and they will never get out of it, therefore the "key" is broken. They see all the powers (the fans, the success, the media), and they just look at each other and know what each of them thinks: They want the time to pass by, but still stay where they are now, because it's where they want to be. They know that even though fame can be hard, nothing will be able to tear them down, because they have each other, and most importantly their fans.