Why is query runtime so large compared to execution time and planning time?

Question

PostgreSQL

I did explain analyze of my query, it shows: scheduling time 0.196ms and execution time 0.072ms in total is 0.268ms but why do I show total query runtime as much as 2 seconds? Moreover, I took measurements in the application itself and sometimes the response time reaches up to 2s, although basically the request is executed to the application in 0.3s, but sometimes it jumps up to 2s and 4s, maybe, why is that? Iron is not the weakest, 128 RAM, 64 cores, 14 version of postgresql, ubuntu20

The request itself

SELECT blacklisted_id FROM blacklist_persons WHERE user_id = $1 AND place = $2 AND blacklisted_id = $3 LIMIT 1