Optimizing query for large number of rows in mysql

ALTER TABLE tbl_content ADD INDEX idx_state (state);
ALTER TABLE tbl_content ADD INDEX idx_catid (catid);
ALTER TABLE tbl_content ADD INDEX idx_section (sectionid);
ALTER TABLE tbl_content ADD INDEX idx_publish (publish_up);
ALTER TABLE tbl_content ADD INDEX idx_state_catid_publish (state, catid, publish_up);

Source:

https://dba.stackexchange.com/questions/93216/optimizing-query-for-large-number-of-rows-in-mysql