Those settings are more for the client applications than they are for the API oauth token. I believe the Log inactive users out is specific to web app where if a user hasn't performed an action in that time frame, they log the user out and invalidate the token.
As for your actual question, there is no way to extend the life of a single OAuth access token. However you can receive a new access token by using the refresh oauth flow without requiring your user's to log in again. This page documents how you can use the refresh token received from your original /oauth/token request to get a new access token.