问为什么mysql查询需要很长时间才能收到结果？

EN

SELECT a.rNum,
        a.cDate,
        a.cTime,
        a.aNumber,
        a.bNumber,
        a.duration,
        a.tag,
        a.aNumber2,
        a.bNumber2,
        'hasMatch',
        a.concatDate,
        a.timeMinutes
FROM tableOne a
INNER JOIN
tableTwo b ON a.aNumber2 = b.aNumber2 
AND a.bNumber2 = b.bNumber2
WHERE a.hasMatch = 'valid'
AND (a.duration - b.duration) <= 3  
AND (a.duration - b.duration) >= -3 
AND TIMEDIFF(a.concatDate,b.concatDate) <= 3
AND TIMEDIFF(a.concatDate,b.concatDate) >= -3
LIMIT 0,100;