help in interpreting explain command

hi,

suddenly our percona mysql db giving high cpu usage. although the query down here wasn’t in slow query log before.

‘1’, ‘SIMPLE’, ‘cw’, ‘index’, ‘PRIMARY’, ‘mdl_coursect_cousec_uix’, ‘16’, NULL, ‘1’, ‘Using index’
‘1’, ‘SIMPLE’, ‘md’, ‘ref’, ‘PRIMARY,mdl_modu_nam_ix’, ‘mdl_modu_nam_ix’, ‘62’, ‘const’, ‘1’, ‘Using where; Using index’
‘1’, ‘SIMPLE’, ‘m’, ‘ALL’, ‘PRIMARY’, NULL, NULL, NULL, ‘23’, ‘Using join buffer (Block Nested Loop)’
‘1’, ‘SIMPLE’, ‘cm’, ‘ref’, ‘mdl_courmodu_cou_ix,mdl_courmodu_mod_ix,mdl_courmodu_ins_ix’, ‘mdl_courmodu_ins_ix’, ‘8’, ‘moodle_15161.m.id’, ‘1’, ‘Using where’

as i’m not an expert in db. someone can interpret for me?