SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53e56a1fef9b8fed420bbd46c61976004a52ab750e5442c941937b9835a16f0d' 
  AND token = 'cOXW94IQApOZaWNC9kEKz/uLkrD8y+9GwVORLVxgBQo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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