SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a93b896811c1d849512da1baf2d57faea64de2f35a46e18be0ccd78a528731f' 
  AND token = '+fJBJv7TZu/gg+aObZfSn7G82xYSOohYiv6iwtI9LwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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