I can't figure out how to set the proper indexes for MySQL subqueries

Here is my query:

SELECT IFNULL(d_source,"TOTAL") AS SOURCE, IFNULL(SUM(STORECOUNT),0) AS STORECOUNT, IFNULL(SUM(STORECOUNTCP),0) AS STORECOUNTCP, IFNULL(SUM(TDP),0) AS TDP, IFNULL(SUM(TDPCP),0) AS TDPCP, IFNULL(ROUND(SUM(TDP) / SUM(STORECOUNT),2),0) AS AVGUPCSPERSTORE, IFNULL(ROUND(SUM(TDPCP) / SUM(STORECOUNTCP),2),0) AS AVGUPCSPERSTORECP, IFNULL(ROUND(SUM(TOTAL) / SUM(STORECOUNT) / 8.57,2),0) AS AVGUNITSPERSTORE, IFNULL(ROUND(SUM(CPTOTAL) / SUM(STORECOUNTCP) / 4.29,2),0) AS AVGUNITSPERSTORECP, IFNULL(ROUND(SUM(TOTAL),0),0) AS TOTAL, IFNULL(ROUND(SUM(CPTOTAL),0),0) AS CPTOTAL, IFNULL(ROUND(SUM(PPTOTAL),0),0) AS PPTOTAL,  ROUND(sum(2016_Apr),0) AS 2016_Apr , ROUND(sum(2016_May),0) AS 2016_May  FROM (SELECT d_source,key_retailer,
    COUNT(DISTINCT(CASE WHEN datetimesql BETWEEN '2016-04-01' AND '2016-05-31' AND unit_sales > 0 THEN store_id  END)) STORECOUNT,
    COUNT(DISTINCT(CASE WHEN datetimesql BETWEEN '2016-05-01' AND '2016-05-31' AND unit_sales > 0 THEN store_id END)) STORECOUNTCP,
    COUNT(DISTINCT(CASE WHEN datetimesql BETWEEN '2016-04-01' AND '2016-05-31' AND unit_sales > 0 THEN CONCAT(upc,store_id) END)) TDP,
    COUNT(DISTINCT(CASE WHEN datetimesql BETWEEN '2016-05-01' AND '2016-05-31' AND unit_sales > 0 THEN CONCAT(upc,store_id) END)) TDPCP,
   SUM(CASE WHEN datetimesql BETWEEN '2016-04-01' AND '2016-05-31' THEN unit_sales  ELSE 0 END) TOTAL,
   SUM(CASE WHEN datetimesql BETWEEN '2016-05-01' AND '2016-05-31' THEN unit_sales  ELSE 0 END) CPTOTAL,
   SUM(CASE WHEN datetimesql BETWEEN '2016-04-01' AND '2016-04-30' THEN unit_sales  ELSE 0 END) PPTOTAL,  
    SUM(CASE WHEN datetimesql BETWEEN '2016-04-01' AND '2016-04-30' THEN unit_sales ELSE 0 END) 2016_Apr , SUM(CASE WHEN datetimesql BETWEEN '2016-05-01' AND '2016-05-31' THEN unit_sales ELSE 0 END) 2016_May  FROM storeCheckRecords   INNER JOIN allStores 
         ON allStores.id = store_id  WHERE d_source !='STORELOCATOR' GROUP BY d_source) T GROUP BY d_source WITH ROLLUP

And here is the explain:

id  s_type   table       type   p_keys    key     key_len  ref      rows         Extra
1   PRIMARY  <derived2>  ALL    NULL      NULL    NULL     NULL     2            Using filesort
2   DERIVED  SCR         ALL    store_id  NULL    NULL     NULL     1229950      Using where; Using filesort
2   DERIVED allStores    eq_ref PRIMARY   PRIMARY 4        dfc.SCR  1            Using where

I don't understand what I am missing to stop the search of the entire SCR table and or index it so that it doesn't search all. Thank you for any and all help.