I have set up my table with an index only on done_status(done_status =INT), when I use EXPLAIN SELECT * FROM reminder WHERE done_status=2 i get this back id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE reminder ALL done_status NULL NULL NULL 5 Using where but when I give this command EXPLAIN SELECT * FROM reminder WHERE done_status=1 that's what I get back: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE reminder ref done_status done_status 4 const 2 first time it shows me it uses 5 rows second time 2 rows I don't think the index works, if I understood it right first time it should give me 3 rows. What do I do wrong? SHOW INDEX FROM reminder: Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment Index_comment reminder 1 done_status 1 done_status A 5 NULL NULL BTREE