Mate in 5 Exercise 44

White plays and wins in 2 moves https://lichess.org/UukFtctb

1. a7+ Kc8 2. a8=Q#

Yes, if the black king moved to a8, the game would have been longer than 5 moves

The analysis board does checkmate in 5 moves

1. Bc6 Kc8 2. a7 Rg5+ 3. Bd5 Rxd5+ 4. Kxd5 Kd8 5. a8=Q#

Source:

This publication is in my collection "500 chess puzzles. Mate in 5. Advanced & Expert Level."