SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6edb872451023f385bd08c8ac568e0c5980311d00924b8552120044c27a9cda6' 
  AND token = 'fUy2jyOqQ/XeQa1hIYzGbXRVITHfWA/hcKR8h5D5VgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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