SELECT FOR UPDATE locks whole table

We have the following query:

SELECT certificate_id   INTO TEMP TABLE x_certs   FROM certificate   WHERE cert_status = 0 AND       certificate_id
BETWEEN1111 AND 2222 AND       client_id IN (1, 2, 3)   ORDER BY certificate_id   FOR UPDATE;
 

Is there any reason that this query should lock the entire certificate table? Is there something strange because of the
INclause or because it is going 
 
into a temporary table?  This is a production server running 7.2.2 so perhaps 
it is fixed in 7.3.

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