SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b50823bda3efa7f40183493f44a6e7fbd855ad56f10d8c94d5d5d83f0004fc5' 
  AND token = '3ODVU4jZ0jnRj+WrBBspp6LezbEYJB3sG73KuqVawiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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