SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b818083c8184fb3dda5a94c056d7ebe4be9c3514f586a922be211be4fb53e304' 
  AND token = 'AsSrjMd2nmX9/IQXlvHxGYhVHon0YO2TmQ7W1LvEe1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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