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SELECT 
  a.modifier, 
  a.modifier_type, 
  IF(
    shared_option_variants.variant_id IS NOT NULL, 
    shared_option_variants.modifier, 
    a.modifier
  ) as modifier, 
  IF(
    shared_option_variants.variant_id IS NOT NULL, 
    shared_option_variants.modifier_type, 
    a.modifier_type
  ) as modifier_type, 
  a.variant_id 
FROM 
  cscart_product_option_variants a 
  LEFT JOIN cscart_ult_product_option_variants shared_option_variants ON shared_option_variants.variant_id = a.variant_id 
  AND shared_option_variants.company_id = 1 
WHERE 
  1 
  AND a.variant_id IN (
    217615, 232990, 232997, 232597, 235995, 
    236021, 236048, 232605, 232643, 232632, 
    232621, 232712, 232725, 232738, 232764, 
    232268, 236062, 236088, 221146
  )

Query time 0.00066

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "shared_option_variants",
      "access_type": "system",
      "possible_keys": ["PRIMARY", "company_id"],
      "rows": 0,
      "filtered": 0,
      "const_row_not_found": true
    },
    "table": {
      "table_name": "a",
      "access_type": "range",
      "possible_keys": ["PRIMARY"],
      "key": "PRIMARY",
      "key_length": "3",
      "used_key_parts": ["variant_id"],
      "rows": 19,
      "filtered": 100,
      "attached_condition": "a.variant_id in (217615,232990,232997,232597,235995,236021,236048,232605,232643,232632,232621,232712,232725,232738,232764,232268,236062,236088,221146)"
    }
  }
}

Result

modifier	modifier_type	variant_id
0.000	A	217615
0.000	A	221146
0.000	A	232268
0.000	A	232597
0.000	A	232605
0.000	A	232621
0.000	A	232632
0.000	A	232643
0.000	A	232712
0.000	A	232725
0.000	A	232738
0.000	A	232764
0.000	A	232990
0.000	A	232997
0.000	A	235995
0.000	A	236021
0.000	A	236048
0.000	A	236062
0.000	A	236088