Retro 80s computer keyboard broken
The circuit doesn't need a clock, at least not for the key matrix.

ICs 115, 117 and 118 are priority encoders, probably 74LS148. They are strictly combinatorial circuits that generate a binary code that represents which input line is being pulled down.

The 'LS273 (124) latches the outputs of the encoders, and the comparators ('LS85, 119 and 120) above and below it are checking to see whether the current input of the latch is different from its output. This "key change" detection probably triggers the debounce logic across the bottom of the diagram, which I have not tried to analyze in detail.

The EPROM is only being used to translate from the 7-bit matrix position produced by the encoders into (probably) ASCII, based also on things like shift, ctrl, and capslock.