SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b56d47cc6f3999c81cc31b2cacaf8c247cf3d7c6863f882ffd15259ea3b98bc' 
  AND token = '5Dh2ZLKWQgCtJjfHM+sfQxxBj8u7JCnYIAMWwefNwkY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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