SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12bcacd4414418cd123280880b849838f22d6b7a591417cd7ee73b215f67af86' 
  AND token = 'leXvdvgEmXVbxGzqxS2P+pcyNWh86dgq3eHp6nLiZTs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}