SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3686b84239a5de8346970c810fe1d348a20bd854a2ce32914752fc8e3296711' 
  AND token = 'SyQIEw8rA9ke0Z9v3j/mXoNrYnSvwUjNlZWxif8Ge80=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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