Jeow, For year 2, you have to complete Petra Venj's questlines to unlock her weekly bounties. You will earn a guaranteed X 1 key per week, per character for completing a queen's wrath bounty. Also, you can occasionally earn a key from Variks the Loyal (Vandal at the Reef), if you are rank 3 (house of judgment) or above. You can take each of your characters to Variks X 1 per week to receive a reward package (if you are rank 3). You will obtain glimmer, other consumables (ether seeds), ammo synthesis, etheric light, and occasionally a key.

I still get them from doing bounties from Petra in the Reef. I believe I also got one when I leveled up her reputation recently. Admittedly, I often forget to even visit the Reef. It is kind of a ghost town now. So sad.