SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8825d8793f3f5637f456625da02312771d6f75a3df772db09bffa2f52c97fd90' 
  AND token = 'SgDkNVkEHFieei4IidIXnzdlnFhF4yh+CcptVKBMYMY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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