How to avoid compiler warning `unused lexical variable' for `dolist' or `dotimes'?

[Jean Louis]

(defun db/table-id-plist (table id pg)
  "Returns plist for table by its table_id"
  (let* ((columns (db/table-columns table pg))
         (sql (db/sql-by-columns table columns id))
         (values (rcd-sql-first sql pg))
         (values (append values nil))
         (length (length columns))
         (plist '()))
    (dotimes (i length plist)
      (setf plist (plist-put plist (intern (elt columns i)) (elt values i))))))


What is proper way to avoid this warning in `dolist' or `dotimes':

rcd-db.el:841:1: Warning: Unused lexical variable ‘i’

Declaring variable `i' in `let' before `dolist' or `dotimes' did not
help.

Jean