The closest thing is Article I, Section 3.7 (which was already in your reply):
Judgment in Cases of impeachment shall not extend further than to removal from Office, and disqualification to hold and enjoy any Office of honor, Trust or Profit under the United States: but the Party convicted shall nevertheless be liable and subject to Indictment, Trial, Judgment and Punishment, according to Law.
That only states a person who was impeached and removed from office is still subject to criminal proceedings afterwards, not that indictments can’t occur before or during impeachment.
In 1998, Kavanaugh, current Supreme Court nominee, said:
After the Senate has concluded, I would send a letter to the attorney general explaining that we believe an indictment should not be pursued while the president is in office.
There has never been a judicial ruling (i.e., a Supreme Court decision) on whether a sitting president can be indicted. If there had been, then then-lawyer Kavanaugh wouldn’t have used “believe” and would’ve observed the Supreme Court’s verdict instead.
This won't be resolved until the Supreme Court hears United States v. Trump, if it ever comes to that. And in that instance, i̶f̶when Kavanaugh is confirmed, then we'll (erroneously) get a ruling that a sitting president can't be indicted.