Storing and searching user location using latest MySQL 5.7 spatial features

Question

I want to use MySQL spatial features to store user location. I have read about MySQL spatial geometry data type. According to this article this works very well in MySQL 5.7 http://mysqlserverteam.com/mysql-5-7-and-gis-an-example/

Have anyone used it and would recommend it? Is InnoDB good engine type for this kind of think? I want this to be efficient, fast and reliable.

What would be the best table structure to store the location? I thought I could do something like that.

CREATE TABLE locations (
    id INT(11) AUTO_INCREMENT,
    location geometry NOT NULL, # I am guessing this will store the latitude and longitude,
    city varchar(100) not null,
    county varchar(100) not null,
    postcode TINYTEXT,
    PRIMARY KEY(id),
    SPATIAL KEY i_location (location)
) ENGINE=InnoDB DEFAULT CHARSET=latin1

CREATE TABLE user_location (
    id INT(11) AUTO_INCREMENT,
    userId INT(11) NOT NULL,
    locationId INT(11) NOT NULL,
    PRIMARY KEY(id)
) ENGINE=InnoDB;

Any thoughts on that?

Then when I will need to use this location for example find users near me within 50 miles. I was thinking to use something similar to examples given in this article http://mysqlserverteam.com/mysql-5-7-and-gis-an-example/

Would that work fast when the database gets huge?

I want to build this solid as I don't want to worry about the speed as the database grows.

Any ideas will be appreciated

EDIT:

I forgot to add that I only want to store UK location