SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57ebd3204ec0828496f98ca05acb0a8f3e840d4d5a3370669d50ba1c79e91be7' 
  AND token = 'l7P4GAxF0UJQimEkOFf1HY3pXlTnIK2VNpEa1zO3/y4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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