There are any number of things you can do to lock in your current level of compensation while systematically lowering your effort. You can:
* Get faster at producing the outcomes the business is looking for; the easiest way to do this is often to examine your entire work product, spend cycles to isolate the bits that the company is actually valuing, and stop wasting time producing things the company doesn't truly value. A less effective but more time-honored (by geeks) approach to this strategy is "automation".
* Take steps to pivot your role in the company to one that produces outcomes the company values similarly to your current one, but that require less effort on your part.
* Take steps to gradually lower the bar on what's expected of you.
You didn't ask me, but I categorically disagree with the idea that hard work correlates to better pay in a typical company.