SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a91e71c0f5afdb720d397867cc01b053a833bc9ed5982bc8b02668bcf590a754' 
  AND token = 'UhZbt+GILocbAjMOzG9RxS7NAXbzPBLckqrtO3WsWmw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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