SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '3b6af5e16891c362bcd8f9c31bd009e1dcef6a036390dda57f74cae26f5d49f0' 
  AND token = 'vqYAv+HIeOCz/prHvig9V44kUc2UiR0XhDcmeZQaJlI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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