It has been serviced by Lexus every 10,000 miles up to 54,000 miles so it needs a 60,000 miles service although you are correct due to its age it should be 90,000 mile service. As I know it hasn't had it's spark plugs changed I would rather have them done now. I have been quoted £477 for 60,000 mile service including changing spark plugs from an independent Lexus garage.