SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5441f462fe0f750c841810264f836eee824082fca28854c60cfd1291d172bc97' 
  AND token = 'zr/unHARkRzVZ3Yzi1dqERuK2WgK+7Z5De9RpMjZc8Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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