SELECT 
  category_id, 
  parent_id 
FROM 
  cscart_categories 
WHERE 
  parent_id IN(
    1206, 1190, 1183, 978, 1204, 1194, 1199, 
    1213, 1202, 1201, 1214, 1207, 1191, 
    1184, 1205, 1195, 1203, 1200, 979, 1208, 
    1192, 1185, 1196, 980, 1209, 1186, 981, 
    1193, 1197, 1210, 1187, 982, 1198, 1211, 
    1188, 983, 1212, 984, 1189, 985, 986, 
    987
  ) 
  AND category_id != 264

Query time 0.00030

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost": 0.0457204,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_categories",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "parent", "p_category_id"],
          "key": "parent",
          "key_length": "3",
          "used_key_parts": ["parent_id"],
          "loops": 1,
          "rows": 64,
          "cost": 0.0457204,
          "filtered": 100,
          "attached_condition": "cscart_categories.parent_id in (1206,1190,1183,978,1204,1194,1199,1213,1202,1201,1214,1207,1191,1184,1205,1195,1203,1200,979,1208,1192,1185,1196,980,1209,1186,981,1193,1197,1210,1187,982,1198,1211,1188,983,1212,984,1189,985,986,987) and cscart_categories.category_id <> 264",
          "using_index": true
        }
      }
    ]
  }
}

Result

category_id parent_id
1183 978
1184 978
1185 978
1186 978
1187 978
1188 978
1189 978
1190 979
1191 979
1192 979
1193 979
1194 980
1195 980
1196 980
1197 980
1198 980
1199 981
1200 981
1201 982
1202 983
1203 983
1204 984
1205 984
1206 985
1207 985
1208 985
1209 985
1210 985
1211 985
1212 985
1213 986
1214 987