Ramayana: For Sita, the turnkeys were scary-looking demonesses who materially threatened her with dire consequences if she didn’t submit to Ravana.
Mahabharata: Bhishma told Duryodhana that Krishna had been doing miraculous things right from birth: when he was born in a prison cell, the turnkeys mysteriously fell asleep, giving his father the chance to slip away and take him to the safety of Vrindavan.
Bhagavad-gita: In material existence, the turnkeys that bind us are our own attachments to our body and to the various objects we wish to enjoy through the body.
A seeker of truth is ever vigilant to appoint the turnkey of his intelligence to guard the wicked prisoner of his mind, which is always planning its escape to join the comradeship of the senses for an unrestricted material enjoyment.
The intelligence has to already be a turnkey to articulate a thought like that.