SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '839afaaca8860941989f5a5cb788b1e29dffd7a065b67a4df7f3e4a5905e03d3' 
  AND token = 'wQZ+UfKj4ByNWu/vWA/lN9HQaexhnokmQ9mJhDhk74w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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