You said connect to an irrigation valve. Do you mean an electrical valve, so that the timer need on switch power?
This one has fifteen minute increments.
https://www.amazon.com/dp/B07G129BH2/
This one has nearly infinite control. However, I think it defaults to night only, but blocking the sensor should keep it active all the time.
https://www.amazon.com/dp/B07G129BH2/
You may find more by looking at hydroponic suppliers. Some hydroponic modes can call for short on times.
