SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be217371a87f0c37216314a5b27dce2f962262fae1b0ace6df951270072b1b95' 
  AND token = 'MCVP/631exaaBAmrwzokSxvzifqRyNe6hHb1tmlOes0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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