SELECT 
  product_id 
FROM 
  cscart_product_popularity 
WHERE 
  product_id IN (
    12378, 12377, 12376, 12375, 12374, 12373, 
    12372, 12371, 12370, 12369, 12368, 
    12367, 12366, 12365
  )

Query time 0.00057

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "3.12"
    },
    "table": {
      "table_name": "cscart_product_popularity",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "total"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 14,
      "rows_produced_per_join": 14,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "1.72",
        "eval_cost": "1.40",
        "prefix_cost": "3.12",
        "data_read_per_join": "448"
      },
      "used_columns": [
        "product_id"
      ],
      "attached_condition": "(`test2_gaseus`.`cscart_product_popularity`.`product_id` in (12378,12377,12376,12375,12374,12373,12372,12371,12370,12369,12368,12367,12366,12365))"
    }
  }
}