And who’s to say that those ships weren’t around during Archer’s time? We do know that Klingons ships tend to be around for at least a century.
And there was a mention from Vulcan Ambassador Tos that if he hadn't negotiated the return of Klaang to Qo’noS, a squadron of Klingon Warbirds would have been sent to Earth in the series premiere of ENT. So, the Klingon Warbirds were intended to be around during the time of ENT; we just never got the chance to see them onscreen during the show when it aired.
And there was a mention from Vulcan Ambassador Tos that if he hadn't negotiated the return of Klaang to Qo’noS, a squadron of Klingon Warbirds would have been sent to Earth in the series premiere of ENT. So, the Klingon Warbirds were intended to be around during the time of ENT; we just never got the chance to see them onscreen during the show when it aired.