Keystone technically is the top stone of an arch. In this case I believe it is another abstract item / person of importance
your picture:
Shows the main orders and steps of the Associated Masonic orders
Masonry 3 steps
Left side is Scottish Rite 32 deg (33rd is honorary)
Right Side is York Rite
Center is Shriners (?)
It is very important to note that the 3rd degree of Masonry is the Highest Degree, the others are not higher per se but more of a window dressing / further education (modern day)
Zac from Info wars said the Q team was more than one, interestingly 3 Civ only and that they were pillars. It may blow your mind but they may be:
Junior Warden
Senior Warden
Worshipful Master
Would not surprise me