SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '517ffff91815251ac63a09308c7677ab54d4ed6123c324512d2481511e5caf20' 
  AND token = 'xQY1Vz1CowUykFeaBGfzOl6BJlGZ/I21TJax9jxc8Ws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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