SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68944860b997b75c7b9237d6cc79b44d3fa1f53e7a583bc9cabf5917cb8f87e1' 
  AND token = 'CKAFVjEjD/EuJJMlnopZz8Clxc7OvHaWF+Bv5UwkLtE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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