From http://blog.bobbyallen.me/2015/04/04/get-nearest-places-from-mysql-with-latitude-and-longditude/

2-zpusob.sql

// Praha, Drazdany

SET @lat1 = 50.0598058;
SET @lat2 = 51.0769658;
SET @lng1 = 14.3255396;
SET @lng2 = 13.6325016;

select
6371 * 2 * ASIN(SQRT(
            POWER(SIN((@lat1 - abs(@lat2)) * pi()/180 / 2),
            2) + COS(@lat1 * pi()/180 ) * COS(abs(@lat2) *
            pi()/180) * POWER(SIN((@lng1 - @lng2) *
            pi()/180 / 2), 2) ));

lat-lng.sql

-- Set your users current location in LAT/LONG here
set @lat=51.891648;
set @lng=0.244799;

-- The main SQL query that returns the closest 5 airports.
SELECT id, icao, lat, lng, 111.045 * DEGREES(ACOS(COS(RADIANS(@lat))
 * COS(RADIANS(lat))
 * COS(RADIANS(lng) - RADIANS(@lng))
 + SIN(RADIANS(@lat))
 * SIN(RADIANS(lat))))
 AS distance_in_km
FROM airports
ORDER BY distance_in_km ASC
LIMIT 0,5;