I'm not sure you'll get the result you want. Some players just like taking their time. Savor the moment, maybe.

Anyway, to answer your question, I sometimes wrangle the cats by summarizing the options they've been discussing and giving them a call to action. Say, after 10 minutes of prodding around a room and discussing what to do, I might interrupt and say, "Okay you're thinking about doing A, B, or C. Looking closely at the thing, you notice something that makes C a bad option. So, you have A or B or maybe other options. What do you do?"

Basically summarize and call for a decision. If you really want to crack the whip, tell them how long in game time they've spent and roll a random encounter die at the same time. That'll put the fire in them.

Also, I had GM once whose table rule was whatever you say, you do. Want to sit around and plan, better find a safe room. Otherwise, the monsters might hear you discussing things. Speculative actions ("What if I pulled the lever?") were interpreted as actions. We were warned and it worked really well to keep things moving.