SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7945f0aff272eab7e6d71e90a64cfc634688efd0892c3aa6f7bcce9e15568ace' 
  AND token = 'HRbyNqHYX23td3mhrwskwjak8ub3JrThNURuFxMRAd0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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