SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31ab9f19451a5be0b70a37de63269b2ae8595cce72416cd4b87b06d8b3a2c6fc' 
  AND token = 't2wInmC1J+vPhkRISTyoLcYA4/PXYJubtq+hoJosgv8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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