SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb31e183636955c563909dc86328f51c9e130fe56200b18b668378da452bcca8' 
  AND token = '8jd47KjGTrrgyVlpxlHTwhL8RbEhsFqBXwXRsIRcdeA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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