SELECT 
  object_id 
FROM 
  cscart_images_links 
WHERE 
  object_type = 'abt__ut2/menu-with-icon'

Query time 0.34598

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "322028.00"
    },
    "table": {
      "table_name": "cscart_images_links",
      "access_type": "index",
      "key": "object_id",
      "used_key_parts": [
        "object_id",
        "object_type",
        "type"
      ],
      "key_length": "81",
      "rows_examined_per_scan": 1585950,
      "rows_produced_per_join": 158595,
      "filtered": "10.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "290309.00",
        "eval_cost": "31719.00",
        "prefix_cost": "322028.00",
        "data_read_per_join": "14M"
      },
      "used_columns": [
        "object_id",
        "object_type"
      ],
      "attached_condition": "(`webmarco`.`cscart_images_links`.`object_type` = 'abt__ut2/menu-with-icon')"
    }
  }
}

Result

object_id
0
153
154
155
159
162
178
194
195
196
201
203
208
209
210
211
212
213
214
216
219
220
221
222
223
229
233
234
238
242
243
244
245
246
247
251
252
253
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269