I have tapped into the logging system I made and now you should get email notifications when you win a new key. It will tell you what type of key it is and have a link to the keys section to redeem it.
To win new keys, you just have to play the game.
Every 4 hours, you have a 1 in 10 chance of winning a key as soon as you login.
As you play, you have a 1 in 120 chance of winning each minute you are playing.
This *should* average out to winning a new key for every 2 hours of playtime.
Drop rates are as follows:
1 in 3.5 for a common Blue
1 in 3.5 for a common White
1 in 7 for an Uncommon Red
1 in 7 for an Uncommon Green
1 in 9 for a Rare blue
1 in 35 for an Ultra Rare Purple.
Given these drop rates, you can expect ~70 hours of playtime to get a complete set, assuming perfect drops.