SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99e260ce2bddf968fdd21701af14afdfdc51abe1939e9dccf5f5e647044ac374' 
  AND token = 'DWyu0wHVW4JQqOzlPSYkiJFGXVQhtE5dLiG90uKnQoI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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