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 (
    12, 162, 159, 158, 240, 238, 239, 245, 
    242, 243, 214, 217, 218, 206, 207, 198, 
    199, 136, 65, 64, 63, 66, 62, 134, 135, 
    205, 129, 127, 131, 121, 103, 33, 32, 
    182, 246, 208, 229, 211, 210, 209, 71, 
    70, 69, 68, 67, 215, 226, 213, 155, 153, 
    154, 228, 190, 189, 168, 167, 169, 165, 
    166, 86, 106, 105, 247, 101, 176, 28, 
    146, 147, 156, 157, 148, 149, 174, 171, 
    280, 282, 278, 102, 30, 29, 124, 194, 
    178, 248, 140, 141, 144, 143, 142, 26, 
    35, 36, 46, 45, 44, 13
  ) 
  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 0.00118

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "sort_key": "cscart_product_prices.product_id",
      "temporary_table": {
        "table": {
          "table_name": "cscart_product_prices",
          "access_type": "ALL",
          "possible_keys": [
            "usergroup",
            "product_id",
            "lower_limit",
            "usergroup_id"
          ],
          "rows": 253,
          "filtered": 58.34994507,
          "attached_condition": "cscart_product_prices.lower_limit = 1 and cscart_product_prices.product_id in (12,162,159,158,240,238,239,245,242,243,214,217,218,206,207,198,199,136,65,64,63,66,62,134,135,205,129,127,131,121,103,33,32,182,246,208,229,211,210,209,71,70,69,68,67,215,226,213,155,153,154,228,190,189,168,167,169,165,166,86,106,105,247,101,176,28,146,147,156,157,148,149,174,171,280,282,278,102,30,29,124,194,178,248,140,141,144,143,142,26,35,36,46,45,44,13) and cscart_product_prices.usergroup_id in (0,1)"
        }
      }
    }
  }
}

Result

product_id price
12 3600.000000
13 1440.000000
26 4200.000000
28 12000.000000
29 24000.000000
30 42000.000000
32 36000.000000
33 20400.000000
35 3840.000000
36 6120.000000
44 3000.000000
45 8880.000000
46 2520.000000
62 25200.000000
63 22800.000000
64 22800.000000
65 12000.000000
66 46800.000000
67 40800.000000
68 96000.000000
69 63600.000000
70 60000.000000
71 63600.000000
86 43080.000000
101 22680.000000
102 35400.000000
103 2880.000000
105 20400.000000
106 21600.000000
121 2160.000000
124 551400.000000
127 573480.000000
129 215880.000000
131 149880.000000
134 10800.000000
135 0.000000
136 0.000000
140 12000.000000
141 12000.000000
142 48000.000000
143 9600.000000
144 12000.000000
146 5400.000000
147 5400.000000
148 26280.000000
149 10800.000000
153 6000.000000
154 48000.000000
155 9600.000000
156 35880.000000
157 59880.000000
158 570000.000000
159 1365000.000000
162 3930000.000000
165 72000.000000
166 90000.000000
167 72000.000000
168 210000.000000
169 90000.000000
171 59880.000000
174 12120.000000
176 77880.000000
178 840.000000
182 840.000000
189 210000.000000
190 108000.000000
194 1320.000000
198 2160.000000
199 3600.000000
205 18000.000000
206 21600.000000
207 5040.000000
208 9960.000000
209 13200.000000
210 10800.000000
211 36000.000000
213 35400.000000
214 116640.000000
215 131400.000000
217 73320.000000
218 55200.000000
226 32400.000000
228 42000.000000
229 36000.000000
238 66240.000000
239 66240.000000
240 59880.000000
242 29880.000000
243 29880.000000
245 699.000000
246 48000.000000
247 39540.000000
248 44680.000000
278 3000.000000
280 3600.000000
282 2799.000000