SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ea56441f819f17e05099a4e34efa6bd687679444bbefa37d40951933917b099' 
  AND token = 'HDO/S+jRgW+n2e4SZZFXCDeNQJPjuQTdtn7ggo5tJCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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