Judging by the results of a quick Google search (https://stackoverflow.com/questions/8282788/what-does-select-n-sql-no-cache-from-mytable-mean-in-in-mysqls-slow) these queries come from mysqldump saving the dat abase. (Part of your backup system I guess?)
I am pretty sure Moodle did not execute those queries, because there is no mention of SQL_NO_CACHE anywhere in the code.