How are keys awarded?

Be good, play games, get keys. It's that simple.

That's pretty much it. As long as your account is in good standing (no recent bans or whatever), you'll receive fragments randomly throughout the month.

Supposedly you get exactly the same amount of keys you used to, which would mean you just get them randomly from wins in decreasing frequency until the month resets. But they've also implied that the mechanism is different now (which would mean you DON'T get the same number of keys anymore depending on how you play the game) and it's kinda hard to spade since you don't actually get your fragments until your next login.