There is a “Find Material tool” in viewport tab menu.
But where is button? Or any shortcut key?

Thanks!

There is a little “down” arrow next to the material slot of any object or Material node. If you click that icon it will “jump” you to the SHOP network where the material resides.

Generally it should also show up in the tab menu in obj path or the viewport. If i am not wrong?

you can assign a shortcut by adding the tool in the shelf and ctrl-alt-shift click on it to assign your custom shortcut.