SELECT 
  category_id, 
  parent_id 
FROM 
  categories 
WHERE 
  parent_id IN(
    2013, 1948, 1949, 1950, 1951, 1968, 1952, 
    1953, 1954, 1955, 1956, 1957, 1958, 
    1959, 1960, 1961, 1962, 1963, 1964, 
    1965, 1966, 1967, 1969, 1970, 1971, 
    1972, 1973, 1974, 1975
  )

Query time 0.00064

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "6.45"
    },
    "table": {
      "table_name": "categories",
      "access_type": "range",
      "possible_keys": [
        "parent"
      ],
      "key": "parent",
      "used_key_parts": [
        "parent_id"
      ],
      "key_length": "3",
      "rows_examined_per_scan": 29,
      "rows_produced_per_join": 29,
      "filtered": "100.00",
      "using_index": true,
      "cost_info": {
        "read_cost": "3.55",
        "eval_cost": "2.90",
        "prefix_cost": "6.45",
        "data_read_per_join": "75K"
      },
      "used_columns": [
        "category_id",
        "parent_id"
      ],
      "attached_condition": "(`goimagine`.`categories`.`parent_id` in (2013,1948,1949,1950,1951,1968,1952,1953,1954,1955,1956,1957,1958,1959,1960,1961,1962,1963,1964,1965,1966,1967,1969,1970,1971,1972,1973,1974,1975))"
    }
  }
}