SELECT 
  cscart_product_prices.product_id, 
  MIN(
    IF(
      cscart_product_prices.percentage_discount = 0, 
      cscart_product_prices.price, 
      cscart_product_prices.price - (
        cscart_product_prices.price * cscart_product_prices.percentage_discount
      )/ 100
    )
  ) AS price 
FROM 
  cscart_product_prices 
WHERE 
  cscart_product_prices.product_id IN (
    64078, 64192, 64299, 64194, 64182, 64187, 
    64298, 64296, 64184, 64181, 64180, 
    64294, 64193, 64295, 64185, 64327, 
    64191, 64189, 64179, 64190, 64300, 
    64186, 64301, 64195
  ) 
  AND cscart_product_prices.lower_limit = 1 
  AND cscart_product_prices.usergroup_id IN (0, 1) 
GROUP BY 
  cscart_product_prices.product_id

Query time 0.00102

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_prices",
      "access_type": "range",
      "possible_keys": ["usergroup", "product_id", "lower_limit", "usergroup_id"],
      "key": "product_id",
      "key_length": "9",
      "used_key_parts": ["product_id", "usergroup_id", "lower_limit"],
      "rowid_filter": {
        "range": {
          "key": "lower_limit",
          "used_key_parts": ["lower_limit", "product_id", "usergroup_id"]
        },
        "rows": 48,
        "selectivity_pct": 1.779095626
      },
      "rows": 48,
      "filtered": 100,
      "index_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.product_id in (64078,64192,64299,64194,64182,64187,64298,64296,64184,64181,64180,64294,64193,64295,64185,64327,64191,64189,64179,64190,64300,64186,64301,64195) and cscart_product_prices.usergroup_id in (0,1)"
    }
  }
}

Result