SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d832e3172d44e9ffaf0e0625b7d02274c4248633c65a08186da42fca65d911b' 
  AND token = '6KU1IvVhE+vq2IE2LAAZ7VZwGtnvCYnTG9jX7x3/EH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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