SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8269841c65b65fc651d904021605ecbb1e312fac82562d5d90955a0db62f1480' 
  AND token = '1bZpiGzOWp5frb0J10uvt+gPBIeFf44dovZrPrXWx1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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