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 = 'vi' 
WHERE 
  pfv.variant_id IN (
    68677, 68676, 68680, 68679, 73999, 73998, 
    74000, 73997, 74600, 74602, 74647, 
    74648, 74685, 74684, 74683, 74682, 
    74681, 74686, 80381, 81657, 81658, 
    81659, 81663, 81664, 81665, 81666, 
    81667, 81668, 81672, 81673, 85635, 
    85629, 85634, 85626, 85636, 85627, 
    85628, 85633, 85632, 85631, 85630, 
    85738, 85746, 85747, 85748, 85739, 
    85740, 85741, 85742, 85743, 85744, 
    85745, 85749, 85757, 85758, 85759, 
    85750, 85751, 85752, 85753, 85754, 
    85755, 85756, 86637, 86638, 86882, 
    86883
  )

Query time 0.00708

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": 67,
          "filtered": 100,
          "index_condition": "pfv.variant_id in (68677,68676,68680,68679,73999,73998,74000,73997,74600,74602,74647,74648,74685,74684,74683,74682,74681,74686,80381,81657,81658,81659,81663,81664,81665,81666,81667,81668,81672,81673,85635,85629,85634,85626,85636,85627,85628,85633,85632,85631,85630,85738,85746,85747,85748,85739,85740,85741,85742,85743,85744,85745,85749,85757,85758,85759,85750,85751,85752,85753,85754,85755,85756,86637,86638,86882,86883)"
        }
      },
      {
        "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 = 'vi'"
        }
      }
    ]
  }
}