SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f363ddbdb621595b485c5b0f72bf01dadfd6a9886c3a440aece98ef455da4b81' 
  AND token = 'UYshzx6AwhpeVKHXr7gu4p7zrYZlHHc2umWAZ40KiyQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}