OKR is a method for implementing strategic changes (change-the-business), not for measuring performance in day-to-day business (run-the-business).
Instead, the performance of day-to-day work (run-the-business) can be measured using KPIs. These indicators are chosen for the long term, are permanently valid, and provide insights and control over the general health of the company. They help to sound the alarm if something goes wrong in the core business and performance does not meet expectations.
In contrast, OKRs are aimed at strategic changes. The objectives and key results are formulated so specifically that they are only relevant for the current period. In the next period, they are replaced by new objectives and key results. This focus on new objectives and metrics in each period enables a targeted focus on the currently most important change (change-the-business).
A good balance between change-the-business and run-the-business is needed to be successful. Therefore, you should not choose between using OKRs and KPIs, but use both – but each for the right purpose!