SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6da638c993ba2ca153d5f86371946e73a3e074e94a771ff9a1ea0c169d4febed' 
  AND token = 'V3jk6n45eRm6uJYBEKlugMov9uILbAX+/XlJqSMWrwc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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