Charger with long usb cable I have ASUS ZENFONE 2 with model no ASUS_Z00LD and type ZE550KL.
I need a adapter and charging cable of at least 2 metre length.
Google is not showing relevant results.
 How do I get one?
If you cannot find a reference to one on the Asus website, then Asus does not make one. Also, longer cables cause loss of current and hence your phone will charge slower.

Most companies these days don't even sell their chargers and cables in open market. They are only bundled with the products and available via authorized service points. So, if you have an Asus point nearby, go check in there.