SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4165003aff7328f1d07df052e85bdcd125603498367b6e7f4a1f4f72491fc70' 
  AND token = 'X0DULFKMPp9WqK6DLk3dxKUyTdUtHGBNN8L9R+bpSag=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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