SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a4465c17d6b4823a7790dd48d7134d691dafae3497ed037f5466eaa506bb873f' 
  AND token = 'BzewgVk1qxjyMULYtVHDHsAPijyygqSkCq76GT6lIuI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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