SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd78baf1914a1d236281c06adcacd37c013935ddcd6be6bc1310ddf423c3935b0' 
  AND token = 'XWGzmVjh7wO+kWukiBcDm0qHneQL0vU8K/2bjHsILlw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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