SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf7a289b0392c9ece503eed42a6d404d7299d9302ae76af9cc89df393961ca89' 
  AND token = 't/edlHYaSfdZZYYWpzIkXbcekkIs/eE05nsM1ZwkSkk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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