Hasura GraphQL 504 error(Gateway Time-out) while run the query in GraphQL console - API explorer tool

While I do the search for user email Id using '_ilike' in Hasura GraphQL console - API explorer tool and also in API calls. Its took too long time to load after 30 seconds its thrown 504 error(Gateway Time-out). Its happens 3/4 times. Sometimes it shows data. I am getting indeterminate results while do the search. That table have 2.3 millions of data in Postgres DB and its gets update every 30 minutes. I tried with indexing also to fetch the data faster that also not work.. Can someone help me out on this...

The report names no repository file, test, or entry point. Start by reproducing the _ilike query in the GraphQL console and API calls against the 2.3-million-row PostgreSQL table, then inspect the reported timeout and indexing behavior; done requires a reproducible diagnosis and a documented fix or configuration change that prevents intermittent 504 responses.

Written by the indexing model from the issue text.