SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ccd4a9b51636110d77b2464c8c2cb9e967b9a368575958b632d5f7f76cc8f7b0' 
  AND token = 'mXuP8l5JMzBLZ9VCjaAYP5rX/VLa2eEamdQ8EKByHU4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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