SELECT 
  product_id 
FROM 
  cscart_product_popularity 
WHERE 
  product_id IN (201, 204, 203, 202, 200)

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_popularity",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "total"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["product_id"],
      "rows": 5,
      "filtered": 100,
      "attached_condition": "cscart_product_popularity.product_id in (201,204,203,202,200)",
      "using_index": true
    }
  }
}