SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44bb34c36583f2a810903ee52a3a4f474b8c0b7e2743f6d08756130fac233eaf' 
  AND token = '/uZo+uWimRln14bUgTfGGYE7PfTVqxozT8Ux/jBIUkw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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