Russia central bank governor Elvira NabiullinaVladimir Pesnya/Epsilon/Getty ImagesRussia's central bank has kept the key interest rate at 21%, bucking expectations of a hike to 23%.Russia's top central banker said she is eyeing "excessive cooling" in the economy.Russia's high interest rates are impacting business investments and profits, business leaders complain.Russia's economy has been running hot on wartime activities, prompting the country's central bank to hike rates up to 21% — but it's now worried about too much cooling.Elvira Nabiullina, Russia's top central banker, expressed that concern on Friday when she kept the key interest rate unchanged.