SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '660748264468138e8460dfe3e83d158c6249a3bbebe9ac39cffb83f44c08b1ec' 
  AND token = '4U2knhqmLQTP5VWUToIIDd8vO2veW6tYl8XHMSq6tQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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