MySQL 空间索引求解

建表语句如下

CREATE TABLE `nearby_user` (
  `id` int NOT NULL AUTO_INCREMENT,
  `name` varchar(30) NOT NULL DEFAULT '',
  `location` geometry NOT NULL,
  PRIMARY KEY (`id`),
  SPATIAL KEY `location` (`location`)
) ENGINE=InnoDB AUTO_INCREMENT=60001 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci

查询语句

explain SELECT name, ST_AsText(location)
FROM nearby_user
WHERE MBRContains(ST_GeomFromText('Polygon((30000 15000,
                 31000 15000,
                 31000 16000,
                 30000 16000,
                 30000 15000))'), location);

60w 数据不走索引，possible_keys 和 key 都是 null

MySQL 版本：8.0.35-0ubuntu0.22.04.1

有了解 MySQL 空间索引的大佬可以解答一下吗？