In 9.5
The authorization rules are those defined for the query statement specified in the EXPLAIN statement. For example, if a DELETE statement is used as the explainable statement, the authorization rules for the DELETE statement are applied when the DELETE statement is explained.
The authorization rules for static EXPLAIN statements are those that apply to static versions of the statement passed as the explainable statement. Dynamically prepared EXPLAIN statements use the authorization rules for the dynamic preparation of the statement passed as the explainable statement.
The current authorization ID must have INSERT privilege on the explain tables.