SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21da82cde6b856f3e8d921a73c18985849154052074361bb398a73919b6b813f' 
  AND token = 'pHGl+hrk6xwrxLX0UuKI6qLr2jqQCgAY4Ka8hb8sb3A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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