SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b99a84181971bf1a74b36bb6d33782a3741a894f0adb3d09f2146b78f57df93' 
  AND token = 'xdCcl/WPVtDJ17VzCfQSd7DZRYx+BUK6Id4C2RrOGog=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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