SELECT 
  pfv.variant_id, 
  pfv.position, 
  pfvd.variant 
FROM 
  cscart_product_feature_variants AS pfv 
  INNER JOIN cscart_product_feature_variant_descriptions AS pfvd ON pfv.variant_id = pfvd.variant_id 
  AND pfvd.lang_code = 'en' 
WHERE 
  pfv.variant_id IN (
    70673, 70672, 70671, 70670, 70669, 71511, 
    71510, 73131, 73130, 73129, 73132, 
    73515, 73514, 74555, 74556, 74554, 
    74558, 74559, 74557, 74570, 74571, 
    74569, 74936, 74935, 74934, 74937, 
    79224, 79225, 79223, 80523, 80524, 
    80525, 80526, 80527, 80531, 84256, 
    84257, 84258, 84259, 84766, 84292, 
    84293, 84418, 84419, 84420, 84421, 
    85235, 85236, 85237, 85973, 85974, 
    85975, 85976, 85977, 85978, 85979
  )

Query time 0.01095

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "pfv",
          "access_type": "range",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["variant_id"],
          "rows": 56,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (70673,70672,70671,70670,70669,71511,71510,73131,73130,73129,73132,73515,73514,74555,74556,74554,74558,74559,74557,74570,74571,74569,74936,74935,74934,74937,79224,79225,79223,80523,80524,80525,80526,80527,80531,84256,84257,84258,84259,84766,84292,84293,84418,84419,84420,84421,85235,85236,85237,85973,85974,85975,85976,85977,85978,85979)"
        }
      },
      {
        "table": {
          "table_name": "pfvd",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["variant_id", "lang_code"],
          "ref": ["dev_db.pfv.variant_id", "const"],
          "rows": 1,
          "filtered": 100,
          "index_condition": "pfvd.lang_code = 'en'"
        }
      }
    ]
  }
}