I would like to know if there´s a way to switch between blending modes in Sketch app through keyboard (hotkey or whatever).
The only way to switch modes right now is a good old fashioned mouse click.
Unfortunately this isn't a feature available (yet) on Sketch as of this posting. Assigning a custom shortcut key is also out of the question since blend modes are not available as menu items.
There is however a healthy community of developers that are working on Extensions to improve Sketch functionality. You can put in an idea request at the Sketch Issue Repository and see if it generates any interest. With any luck, it will be a part of a future release since this is a built-in function of Photoshop already.