SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d692e5d16931e8d0fbfdd73ddd703a359e443b53cde99c29eda694660ee93f8' 
  AND token = '9d/ovj0SGztT3hs53jyszBtkb7ApiMxRMN+KlULcf8E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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