mysql v5.5 index performance
You need a multicolumn index (id, timeC, value) or (timeC, id, value) because existing timeC and defailt id indexes are not sufficient. 

The common rule is to create the index containing all the columns used by JOIN, GROUP BY, ORDER BY and WHERE clauses. The order columns should be listed in the index can vary due to the exact queries, columns cardinality and even the amount of data.