SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51e5a505093d5e99c6e620d367f4f4f7204e596da3bb5960e72cc838a11e3e93' 
  AND token = 'xXke8OvlvO1VgwXOuQowoiPVzX6gK37AsmKhROoqZ0Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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