SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ecf283d15981498906a2a9eaa68a8943b7d6bed83fa83e3b5a13385c5a5497e' 
  AND token = '3XBojwR0zfuXczQtW/oKNwNgfWEhaCfqA0nCLtwqaV0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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