SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '716ed6fe476005de791df5423d1d04a3f32f16dcfb1afb4460be523b27d15c09' 
  AND token = '43aBhq7N6OUaY3+/YV1GvwKVuThvL8wlR+knmoq8wgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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