SELECT 
  product_prices.product_id, 
  MIN(
    IF(
      product_prices.percentage_discount = 0, 
      product_prices.price, 
      product_prices.price - (
        product_prices.price * product_prices.percentage_discount
      )/ 100
    )
  ) AS price 
FROM 
  product_prices 
WHERE 
  product_prices.product_id IN (
    505, 1345, 15944, 66569, 19922, 71647, 
    167573, 46111, 46117, 156908, 46118, 
    246604, 253450, 263753, 247140, 247025, 
    247846, 46462, 204749, 246605, 257457, 
    257455, 257456, 247613
  ) 
  AND product_prices.lower_limit = 1 
  AND product_prices.usergroup_id IN (0, 1) 
GROUP BY 
  product_prices.product_id

Query time 0.00282

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "16.97"
    },
    "grouping_operation": {
      "using_filesort": false,
      "table": {
        "table_name": "product_prices",
        "access_type": "range",
        "possible_keys": [
          "usergroup",
          "product_id",
          "lower_limit",
          "usergroup_id"
        ],
        "key": "product_id",
        "used_key_parts": [
          "product_id"
        ],
        "key_length": "3",
        "rows_examined_per_scan": 24,
        "rows_produced_per_join": 2,
        "filtered": "10.00",
        "index_condition": "(`goimagine`.`product_prices`.`product_id` in (505,1345,15944,66569,19922,71647,167573,46111,46117,156908,46118,246604,253450,263753,247140,247025,247846,46462,204749,246605,257457,257455,257456,247613))",
        "cost_info": {
          "read_cost": "16.73",
          "eval_cost": "0.24",
          "prefix_cost": "16.97",
          "data_read_per_join": "57"
        },
        "used_columns": [
          "id",
          "product_id",
          "price",
          "percentage_discount",
          "lower_limit",
          "usergroup_id"
        ],
        "attached_condition": "((`goimagine`.`product_prices`.`lower_limit` = 1) and (`goimagine`.`product_prices`.`usergroup_id` in (0,1)))"
      }
    }
  }
}