Stepping inside Lexington Bar and Books is a bit of a time warp, and one that its suit-clad patrons appreciate. Although this mahogany-trimmed cigar bar mainly attracts the Park Avenue gentleman (and, on occasion, the lady who accompanies him) dropping by after work or after dinner to sit by the fireplace or listen to soothing jazz, cigar aficionados from all over the city can be found in the leather chairs. Sometimes even smokers under 40 stop by to enjoy the dignified yet congenial atmosphere, where the stuffiness mostly emanates from the pungent tobacco aroma. And, yes, true to the name, there are books — plenty of them. But the lighting is awfully dim, so most visitors limit their reading to the extensive menu of whiskeys, brandies and cigars, and leave Plato’s Republic on the shelves.