SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '403f503219b9c872fd08ed737879b3633641be7170e1140c4ab2f8f25f09dda2' 
  AND token = 'UUHmeXldo8t5vkVGNviFVEr+MUgNR91j3ZJBInQH9G0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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