SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '761a44e9fdeb3dc433875a9aa2fabd9f4e1455e66a6ea1f4f677bef2dea0f9d9' 
  AND token = 'ejHTBwR2YsvVIP10NzL88J5N+Uoc5qvcrbaUs8gIMus=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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