SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '63b715157f2fd61428844b47757b699923e87f43bc258dc19b2cc59df48aacf1' 
  AND token = 'GtUOOQ+4EUOPABO5rboWWsrfvOcsv9ypXUlGKxoOe+o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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