Freezer |       Timestamp      | Temperature_1
     1      2018-04-25 09:45:00       10
     1      2018-04-25 09:50:00       11
     1      2018-04-25 09:55:00       11


Freezer |       Timestamp      | Temperature_2
     1      2018-04-25 09:46:00       15
     1      2018-04-25 09:52:00       13
     1      2018-04-25 09:59:00       12

Freezer |       Timestamp      | Temperature_1 | Temperature_2
     1      2018-04-25 09:45:00       10             15
     1      2018-04-25 09:50:00       11             13
     1      2018-04-25 09:55:00       11             12

SELECT A.Freezer, A.Timestamp, Temperature_1,Temperature_2 From TABLE_A as A
RIGHT JOIN TABLE_B as B
ON A.FREEZER = B.FREEZER
WHERE A.Timestamp = B.Timestamp (this of course doesn't work because timestamps aren't the same)

SELECT Temperature_1
From TABLE_A A JOIN
     TABLE_B B
     ON A.FREEZER = B.FREEZER AND
        A.Timestamp >= DATEADD(minute, -5, B.TimeStamp) AND
        A.Timestamp <= DATEADD(minute, 5, B.TimeStamp) ;