MySQL 8 MBRContains 不使用空间索引

我在Ubuntu和；Windows 10和我都很困惑，为什么这个查询运行得这么慢(大约15秒)，而且没有利用空间索引.我使用的MBRContains几乎与MySQL文档11.4.11 Using Spatial Indexes中描述的完全一样.如果包含在POLYGON(框)中，则表location_coordinate有735k行POINT类型的横向/纵向坐标搜索.

查询:

SELECT long_lat_id, ST_Latitude(long_lat), ST_Longitude(long_lat)
FROM location_coordinate
WHERE MBRContains(ST_GeomFromText(
    'POLYGON((
        40.79607446677 -73.919978196147, 
        40.70923553323 -73.919978196147, 
        40.70923553323 -74.034611803853, 
        40.79607446677 -74.034611803853, 
        40.79607446677 -73.919978196147))', 4326)
    , long_lat);

解释查询

*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: location_coordinate
   partitions: NULL
         type: ALL
possible_keys: long_lat
          key: NULL
      key_len: NULL
          ref: NULL
         rows: 735118
     filtered: 100.00
        Extra: Using where
1 row in set, 1 warning (0.00 sec)

表定义和解释

CREATE TABLE location_coordinate (
    long_lat_id MEDIUMINT UNSIGNED NOT NULL AUTO_INCREMENT,
    long_lat POINT NOT NULL SRID 4326,  
    PRIMARY KEY (long_lat_id),
    SPATIAL INDEX (long_lat)
);


mysql> EXPLAIN location_coordinate;
+--------------+--------------------+------+-----+---------+----------------+
| Field        | Type               | Null | Key | Default | Extra          |
+--------------+--------------------+------+-----+---------+----------------+
| long_lat_id  | mediumint unsigned | NO   | PRI | NULL    | auto_increment |
| long_lat     | point              | NO   | MUL | NULL    |                |
+--------------+--------------------+------+-----+---------+----------------+
2 rows in set (0.00 sec)