IST is amazingly variable, depending on where they decide to park. I had one flight last year where both arrival and departure flights were buses. From the time the inbound flight landed until when we walked into the terminal was around 50 minutes, and involved a substantial tour of the airport in order to finally park at potentially the most distant remote stand possible, and then a seemingly equally long bus trip back to the terminal.

Land and depart from the main terminal, on-time, and 45 minutes might be doable - but there's no way I'd risk it personally, especially if it's below MCT as has been stated.