HTTLReturn per-field remaining TTLs in seconds (-1 no TTL, -2 missing).
| 语法 | HTTL key FIELDS numfields field [field ...] |
| 分组 | hash |
| 参数个数 | -5 |
| 起始版本 | 1.0.0 |
| 标志 | readonly |
| 复杂度 | O(F) fields |
| Redis 兼容性 | differs: silently accepts a stray NX|XX|GT|LT token before FIELDS where Redis rejects it |