SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '36a1c74516f41e086725ac3616a8abf39d94e294b668f8011722bc42907a10a6' 
  AND token = '9YZRmrv+wOnSZVPlNeg97NVdFFlizJxm7sqtck89JUo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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