SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4dfe1cb84924d9b1f39d4de69885e54874a7fb2816d1f807a46338920ef8fa52' 
  AND token = 'JfLJb0mQ2qAMcpLsoJ/jUudkfKxW4ZVr1kzGCIUR544=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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