SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f81f16bffb9039fab48551470a019c21a6ed5c8d1ca30d433441d635870fc4a8' 
  AND token = 'oWQ3ZNG7/Aho6C4S+AtkSyumv5lpX7mVLEwmPTG7VMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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