SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73749c61ed9573b87565bad5a53e78cd58f9bcce8a25625147abad7224b93102' 
  AND token = 'eZXbhV9mFDtIJRa53DRx9TbJKwEAwNzKmXVtPUggB2U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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