in one db I get this bit, which is ideal and very fast:
`"table": {
"table_name": "ptc",
"access_type": "ref",
"possible_keys": [
"PRIMARY",
"product_id"
],
"key": "product_id",
"used_key_parts": [
"product_id"
],
"key_length": "4",
"ref": [
"muscle_dev.pd.product_id"
],
"rows_examined_per_scan": 1,
"rows_produced_per_join": 809868,
"filtered": "100.00",
"not_exists": true,
"using_index": true,
"cost_info": {
"read_cost": "202639.56",
"eval_cost": "80986.80",
"prefix_cost": "735703.40",
"data_read_per_join": "12M"