SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef562e7cf200b6de099d9afa505b030be3256af4af68546f5e35c21d07511a92' 
  AND token = 'cbsBO2MXm4T4cgDF+UKggj5j9csTH/ubtQg+rGHrLIo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}