SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '688c49d6e5a6ddd6b20a2f023ae6ec874a0d2d284b4ee080e97f893fe889d2ef' 
  AND token = 'TBB6K7qHN4WGGuM6s/bpWi7wQbysLoL3+/4qYGFRdrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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