SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '140d06d3983aaae7c9dddfd772f07e34f18c8ced9638758088eb3db049f2761e' 
  AND token = 'wlTn9wpOYI0wDE+pvBLtknsb6ZEyGmdHY5BX+KqqrZQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00011

JSON explain

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