Tymon has made 91 appearances, scoring twice, since joining Swansea from Stoke for about £2m.
Key has scored three times in 79 appearances having arrived from Exeter City, with Swansea paying an undisclosed compensation fee for his services which was decided by tribunal.
Tymon and Key are currently the first-choice options on either side of Swansea’s defence, with academy product Sam Parker providing back-up on the right and no obvious alternative on the left with less than three weeks remaining in the summer transfer window.
Montague was also asked about the future of homegrown winger Cameron Congreve, who is back at Swansea this season having impressed on loan at League Two Bromley last term.
Congreve, 21, sees his contract expire at the end of this campaign.
“We have had conversations with Cam’s agent and Cam himself about his future,” Montague said.
“That’s an active source of discussion at the moment.”