Something like this should work (so long as you have the automatic field date_hour created by Splunk):
index="index_a" sourcetype="pqr" source="prq_source" "Success in api response" earliest=-7d
| where (date_hour>=21 AND date_minute>=30) OR date_hour>=22
| stats avg(call_duration) as avg_call by success_id
If date_hour & date_minute aren’t being automatically supplied by Splunk, you can create them yourself with strftime:
| eval date_hour=strftime(_time,"%H"), date_minute=strftime(_time,"%M")
from User warren – Stack Overflow https://stackoverflow.com/questions/68765482/splunk-panel-showing-graph-for-a-specific-time-range/68772685#68772685
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