I’m not a scientist, but here’s some info and some guessing:
Possibly, there could be a mutation that inhibits the signs of aging like the person wouldn’t get wrinkles. They already say getting wrinkles is partly genetic, and not just a matter of melanin.
As far as internal aging, the way I think about it is our organs get damaged over time, and we stop producing new healthy cells at the same rate. Also, our fighter cells get overwhelmed over time. I think we can see that some people genetically do much better than others. Some families have many people who live long lives, while others have many people in the family who die young. Sometimes we see it’s caused by the environment, but other times it looks to be genetics more than anything.
One problem is cell production when it is out of control (growing and growing) is basically cancer. So, the body needs to keep in balance cell growth and death. People who have better balance, and strong mechanism to detect and fight stray bad cells do better and live longer. The FOXO gene and the study of telomeres would interest you. Here’s a link to a video about FOXO. https://www.pbs.org/video/nova-sciencenow-can-we-slow-aging/
I once read an article about a mutation believed to be the key for surviving the plague. The scientists also determined the same gene protected people from HIV. I’d lay money on a man I worked with who became HIV positive when so many of his friends were diagnosed also. His partner died from it within years. My coworker never became sick. He was positive, but never sick. He was diagnosed in the late 80’s I think, latest would be the early 90’s. He’s in his 80’s now. His father lived to be 99. His family just lives long. Link about the mutation https://www.pbs.org/wnet/secrets/mystery-black-death-clues-evidence/1490/
This link talks about telomeres, but previously I’ve linked a video, it was a program I saw on TV, that was easy to follow, and in my opinion easier to follow. If you can get the search engine to work you might find it. Here is the another link though https://learn.genetics.utah.edu/content/basics/telomeres/