James Doohan was 63 in Star Trek III: The Search for Spock when he played the character 'Montgomery Scott'.
That was over 39 years ago in 1984.
In 2005 he died aged 85, starring in 32 films in his career, 20 of those after Star Trek III: The Search for Spock was first released. If he were alive today he would be 103.
In Star Trek III: The Search for Spock, I think James Doohan looks: