As others have commented, there really isn't a lot going on at KEF, so you should be able to pass through fine.
However, the exception is if a member of your party gets pulled out of line for additional security screening. This happened to me in late August 2022. We had flown from Bergen to KEF getting another plane from KEF to Boston, all on Icelandair. As we were going through staff said I needed to come with them as I had been identified for additional screening, but my husband and kids could not come with me. I was taken to another room and had to take a numbered ticket like a deli counter and sat and waited, and waited, with a large number of others who all had also been on a list for "additional screening". Finally, when my number was called, I was brought into another smaller room and told to remove my shoes and jacket, and the agent opened my carry-on luggage and removed everything, so I then had to re-pack. They then did some kind of swab thing on some items/bag and myself and asked me a bunch of questions. When I finished, I scrambled to my gate as my plane had boarded already. I got on, and my family was not on, I knew they most likely were waiting for me in the airport, but I didn't see them. I asked a few times for the flight staff to page my family as I said they were probably waiting for me to board and I guess Iceland doesn't really do that because they refused and I had to get off the plane and rush around trying to find them. It was not ideal.