SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3f6d86029d917f69236aeb6b56426cba6cafc4782f33f1d3559e245134ae7c7' 
  AND token = 'ZZn98XsrUP0RvSjYGO17XgLhcydc0XxC512lTS8TtiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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