SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'dab9833e114baefc61d4493a6c584cf74cafaa5fcb2d383a4d070f5c0779b53a' 
  AND token = 'WBPjQ3u8P4sqGmAyBqZr0vJdVS8+LKXaWMGNb8NrZns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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