SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '10e1409f6bf755c7d7448dd387e3c22c15a03fbe5a69e3845c561a48b6504201' 
  AND token = '8ACU0ncB+i9gDnV9QDoe6MjYAokmZy4BfmMjEoWO+dI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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