SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '90a087d40ea201a40d992245024baf40805c1954e5ef43fe373b288e692197ec' 
  AND token = 'sMJ8tw/DH9waW1oXzpiF/hFeSaZNQYuV/DgJmS1iKEY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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