I am hazarding a guess, I believe this should do the job
A = { {1, x, 0}, {0, -1, 0}, {0, y, 1} }
It really does not matter what x and y are, they can be chosen arbitrarily and can even be two formal symbols
B = { {0, 0, -$i$}, {$i$, 0, 0}, {0, 1, 0} }
Then A.A= B.B.B = Id
the order of A.B should $A.B$ would be infinite as when $x$ and $y$ are suitably chosen, for example one can choose $x$ and $y$ so that the coefficient of the matrices are $(A.B)^n$ unbounded ?

