How to filter key clicks?
Assuming from your screenshot that the frequency magnitudes of "key clicks" are always higher (brighter) than the normal signal, you could just employ a basic Limiter? In other words, if a frequency magnitude value exceeds a certain threshold, set that frequency value to its last (valid) value. If you wanted to keep the plot from looking unnatural, you could simulate the data where the clicks are or use data from previous samples.