SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8b7e55bb9c5e744a8ee95de5ddb72d3bde705286276bc4a1b46d0c8f4f58dca' 
  AND token = 'mzj3Ii09U4NCXdZb1TNim2uhDTKgoikcIeye2Vmp+P8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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