R60, how long can a timing chain last?

I have a 2014 countryman s with 147,000 km (92,000 miles aprox), it's working just fine, no weird noises, leaks or any other problem, i have fixed every issue that has come (not a single engine or transmission problem, just periferics) and the car is just fine but i keep reading about this timing chain issues when approaching to 100,000k miles and I'm wondering if some of you have passed this mileage without problems?

My mechanic says that i should not worry, he said that his car has 240,000 km (149,000 miles) with the same engine (n18) with no timing chain changes but i've read a lot of cases on the internet when the timing chain snapped, then i ask u, should I do as my mechanic says and just be careful of weird noises or should i try to get a new timing chain as soon as possible?