SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19b9793af24fb11784d3aebaae93241d46915d5c3502e31283fda20332bec208' 
  AND token = 'UDUJy/3GXk7b3by0tfPMHHeETszg2U4drRl3v954aFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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