No, there are no legal international betting sites with no tax in Kenya.
Kenyan betting laws do not allow any betting site to operate within the country without fulfilling their tax duties.
So whether you are a local or international betting site, you are required to pay all the taxes stipulated by the Kenya Revenue Authority.
If you ever run into an international betting site with no tax, know that that bookie is working illegally in this country. It may not be the safest idea to keep using that site.