The title promises a perfect place, but the poem opens somewhere far from one: "where the plague grows." Right away, the word "Utopian" feels ironic, or at least like a hope pointed at a place that doesn't exist yet. The speaker seems to be describing the world as it is, a place of sickness, where desires are heavy, "a rough freight" that has to be hauled around like cargo.
The last two lines turn into a request. "Promise me night comes to pay / one day" sounds tired but still hopeful. Night is imagined as a debtor who owes something, perhaps rest, relief, or an ending to the struggle. The speaker doesn't expect it now, only "one day."
The mood is quiet, bleak, and a little pleading. There's no big outburst, just a small, stripped-down wish. The short lines and missing punctuation make it feel like a murmured prayer, with hope held onto very lightly.