SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9bbf0dfca47b7dcb5cb67229729e34d049bd66a456dc10f47082941aa282717' 
  AND token = 'WT3MdaCyqYIrRb0LIbqOU23iq4qADZpDdOf7JW7CzyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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