Element position of matrix

Hello, how can I find position of known element in matrix if I know that element exists in matrix (column and row index). I tried with match function and I put small value for tolerance (as you can see in attached file test.mcdx) and I'm getting 2x1 for which I know that is not the right position. Also, it would be nice if you propose me the solution with separated index for column and for row.

Thanks in advance!