SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4627810eadb54b91a711de008a5a2089c56e7c35e137d0f3c8e0ee58645ff4e' 
  AND token = 'Bq0zklVtvlqQZKRcZYO+RACQHWws6dKpTlROdJdxp2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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