SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e57ffc03418d938f84f43003356ead781a7f99428af5e84830fd1a565efe90cf' 
  AND token = 'odxmAOJQOlXeN3/sDBwXQ7M7JvZqtUCauqJGoTvINDM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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