SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1577dd28805f5121a00055f147f6f4775278a624d65f861bd8c10c33a5d38263' 
  AND token = 'g7kB0STjiV0v+IBhfOK5LjzW/mVsMuojB9aJAZ67nD8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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