SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '72acfe75465565267cdd00923bd21eb87cdb2bdc62c2123e68108422a085f864' 
  AND token = 'KoxtNgoCxe40EGMYhAK5cUuE62DzNfo7ZvtyJdAQpmU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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