I have new boat and started the Yamaha 150 with the engine up. Maybe went for 30 seconds before I got it in water. There is a stream coming out when it runs. Does that mean I’m likely ok?
I did the exact same thing to my 1999 Yamaha C90 several weeks ago.....ran motor about 30 seconds or so. I pulled the lower unit and the plastic water pump housing had some signs of melting/overheating so I replaced it ($30) and upon recommendation of dealer I also replaced the impeller($30)....so it's a $60 reminder to not do this again! Better replace these 2 items and move on....no need to take chances with your cooling system!...
While you probably did nothing to the impeller it will give you peace of mind to replace it. A dry fire is part of the launch process at marinas, granted it's about 5 seconds long not half a minute.
If you ever notice how tight the impeller vanes are inside that stainless steel pump cup and think of running it dry for several seconds, it's easy to see how it would get hot real fast....the water cools and lubricates the pump....