We’ve been getting a lot of these after upgrading to ACF Pro 5.5+
[Thu Jan 19 16:53:54.101538 2017] [:error] [pid 16791] [client 174.71.6.138:53576] KILLED QUERY (24205 characters long generated): SELECT term_id, meta_key, meta_value FROM wp_termmeta WHERE term_id IN (53722,53002,21495,50501,42593,30713,51753,44120,29279,35579,24417,24163,39308,38849,41677,1161,31304,35560,etc,etc
I noticed that ACF is now utilizing wp termmeta and we have tens of thousands of terms. These terms (the ones queried) seem to be in alphabetical order.
I wouldn’t even know where to start looking for this. Please submit a new ticket https://support.advancedcustomfields.com/new-ticket/