Excel does provide a used range that would get you at least farther than the end, however if you need the exact end, you need to loop through all rows. The Excel used range basically gets you the last cell that ever had something in it, so it might be way past the actual end. I have attached a screenshot of that automation though.

When I have done this in the past with a large number of rows, I create a series of nested loops to go through ever smaller increments. For 30k, I would create one loop that increments the row by 1000. When I get to one that is blank, I would go to another loop that starts 1000 less (or goes backwards, although backwards with the ForLoop component is tricky) and iterates by 100. When that reaches a blank row, then start 100 less and iterate by 1 as going through 99 rows won't take much time. This would mean that for 30,201 rows, you would have to check essentially five cells before you found the correct one.