SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef0c430c0a276325be2431079e0be50d0a69f79583bde284c8eea6ae1da28382' 
  AND token = 'mzouIp9UdtrLYw7rzfOloOHClTS3suUjvN9a3m2iJQU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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