SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3264e9d0c64092c469285ee073f6a0b68f1b8f521f63518af71ccdc7a68618c2' 
  AND token = 'EFFp33nKJh3wgAV3dhPb2464VZl3kWqovmKHYBp8Mdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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