SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9536a82835f9c425a21a4b701d77a248a689b649d9c34fa749baca97f7e9d21' 
  AND token = '67tYnZlTqJYEv4jZ0OBtzrHHUm4FXBefOa83Zrj+WTw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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