SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0cd81749a4f85f4d2b56efb590bf62968e607263974f162c28fc6f1df5d104a' 
  AND token = 'fKpbkB3CWPvVB5mIkDG2P5oP4oH3Z6Qo8wrKGjO/nNI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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