SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bcc71fcbfb2d92a6d511ae43a446ad89b40c9ecee99ac02df24f3b73f984bd52' 
  AND token = 'A7+J6Dm/tlfoSPZOsJe8WaRtNrhMvxGyKcc2IMvpsUs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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