Dark Realistic Book Cover Prompt

I’m looking for a well-crafted text prompt I can drop straight into Midjourney (or a similar AI art tool) to generate the front cover of my new mystery-suspense novel. The scene must be set inside a forgotten, shadow-filled library whose towering shelves fade into darkness. A single antique key—weathered brass, ornate bow, subtle hints of tarnish—takes center stage, lit just enough to reveal that it hides something dangerous. The overall visual treatment must feel realistic rather than stylized, and every detail should heighten a dark, mysterious mood.

Here’s what I need from you:
• A main prompt of about 60–120 words, structured for Midjourney v6 or Stable Diffusion 1.5, specifying camera angle, lighting, color palette, aspect ratio for a standard 6x9" cover, and any negative prompts to avoid cartoonish or low-detail outputs.
• Two alternative prompt variations exploring subtle shifts in composition or lighting while preserving the antique key as the focal point and the hidden library backdrop.
• Quick guidance on parameter settings (e.g., ‑-ar, ‑-v, CFG scale) to achieve crisp, print-ready resolution.

Acceptance criteria
1. Testing your prompt on Midjourney should consistently yield a photorealistic cover with the key unmistakably central and the library’s atmosphere unmistakably dark and foreboding.
2. No modern objects, bright colors, or minimalistic empty spaces should appear unless intentionally described.
3. All three prompts must be unique yet clearly aligned with the novel’s tone.

Deliver your prompts in a simple text file or within the message thread so I can copy-paste and generate the artwork immediately.