SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a7907b743832f8aad24d19ddd86268529cb1676fa356b62702b84d9c9050a008' 
  AND token = 'XL2u8VJ94Zy77UMWkCos+jPbBxGLleVYeAM9BzHUudk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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