SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4647bf5343259742644eecc24adda20c456e2570a742c0eae9571372be8129a7' 
  AND token = 'KiYCP4cTmqXDTUVWyd5IIHo0/W27ZtHYUvbFGRhTu04=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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