SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5fdb7b72919c81bfe283481299975e9648597039728a61e386f8c8df703686b5' 
  AND token = 'EhQeXv5In48NHfH9tCrHT3XeV4voKrv/kf943kIbTVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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