SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b215e41822ef706bbabd6417aa28c2759e5f74f8bfaca5e5a38152a42716a5f1' 
  AND token = '7Cvo2ejBP7V3uOgeY1h9mEnZc1MJZ+okfqTKhubYAjk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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