SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43c2301956606131d883255fac2a269671787b08dbfb573ea6be8cb54641a58b' 
  AND token = '7vO9blkQD7AvB7pMZQXwthS8BKYLHKrPO7OGkewyr/s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}