SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ad683871b9466336ec97df2ad1893349bb25ea7da7144715608d72402d6bcaee' 
  AND token = 'yNaslp5u6pxzKRZ/jvoOuDMUMjm/mfjRnlcmPP/LYzw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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