SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d6d0d91a7e10d21b95bf3f071e72f042aa6198a2cddd8308b5227ddb9483334' 
  AND token = 'N94BhgOYFCvVAjOz2EDuVnctY1uEn6JUGLlTBAmMagY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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