SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8670f867895235824ae14e39c3fa73d191c65f023cf00593774a06388b10066f' 
  AND token = '4+iYqBMhN9UUocyQjXeOKkpQwV2nPy6/0zLAqKAB5OA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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