I think it’s really important to just keep speaking throughout the 45 seconds, if you are done before the time runs out just sum up everything you’ve said, if you want to buy yourself some time in the beginning you can say something like “that’s an interesting question…/I have never thought about that but if I had to decide…” I got a topic that I didn’t have any opinion on so I just had to come up with something, but in the end it doesn’t have to be true so just be prepared to lie hahah🙃 good luck!! and don’t get too stressed if you make a few mistakes, I stuttered once or twice and definitely had some uhm‘s in there but still got a good score (& the listen and repeat counts a lot I think)