SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '0a85391acf15f9a0aece0296108740172a5831fcb22a0bb8be3b87d77b84c031' 
  AND token = 'x/hKDSGGQTC11Ord7gJ5TnVh6+2LucKrVWpY4aA/pfY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00091

JSON explain

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