Russia'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. Analysts polled by Reuters had expected her to hike rates to 23%."Our politics is aimed at prevention of extreme scenarios, which means that we cannot let the economy overheat further," Nabiullina said at a press conference following the rates decision, according to TASS state news agency."It is necessary to make sure that overheating subsides. That said, it is necessary to avoid excessive cooling, which is why we keep a close eye on this," she said.Nabiullina said the central bank kept the interest rate steady as monetary conditions have "tightened even more than was implied by the key rate increase" in October, when the bank raised the rate from 19% to 21%. Russia started the year with its benchmark interest rate at 16%."Consequently, lending growth notably slowed down in November," she said. "We will need some time to assess how steady this deceleration in lending is and how the economy is adjusting to the new conditions."Russian business leaders complain about high interest ratesNabiullina's comments came as Russia's inflation hovered around 8% in the year to November, compared to the target rate of about 4%. Staples, like the price of butter and potatoes, have shot up this year. But the central bank's three straight rate hikes since June may be working, the top central banker signaled."Tough monetary conditions have evolved in the economy, which are to provide for inflation slowdown in coming quarters," she said, per TASS.Russian business leaders have been complaining about the central bank's high interest rates, which they say are stifling business activities.Sergei Chemezov, the CEO of the defense conglomerate Rostec, said in October that record-high interest rates were "eating up" the profit from the company's orders."If we continue to work like this, then most of our enterprises will go bankrupt," Chemezov said.Economic cracks in RussiaEven Russian President Vladimir Putin on Thursday acknowledged that his country's economy is not in a good place and he blamed the central bank and federal government.The Russian leader said that the central bank could have used instruments other than interest rates to cool the economy and that the federal government could have worked with economic stakeholders to improve supply."There are some issues here, namely inflation, a certain overheating of the economy, and the government and the central bank are already tasked with bringing the tempo down," Putin said during his marathon annual press conference.Price rises had been an "unpleasant and bad" outcome, he said.Given the sweeping sanctions against Russia's economy, Nabiullina faces a challenging job to keep Russia's seemingly resilient economy going.Economic cracks are emerging as the Kremlin focuses on shoring up its defense industry for its war in Ukraine but at the expense of other sectors, Alexandra Prokopenko, a fellow at the Carnegie Russia Eurasia Center fellow wrote on Friday.Prokopenko, a former Russian central bank official, wrote that growth momentum could stall next year, with social and fiscal challenges developing into crises around 2026.