SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9396800bffcdb92b534eedf1d6c518e241c10668253ca2b55574c8ef19ae60b2' 
  AND token = 'XNLSE7OO7E8WhowjGvA+fW5YHo6jybyqkZUflkyXc8w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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