SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ea01d35320bf21fcacf8ecd658d549430b8d42c43c80e7d607be419a9d36760' 
  AND token = 'QIqTBbzLMKR6HSPMpPSVMDka1AZ7/JuyVkn33YJZHjc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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