SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df9dfdf752d04b96768cc8730bb733ec24455fc1fb78b7bc1fe12e91fd63a9e9' 
  AND token = 'F1ATmHT5KO4zlVJYthvrB+OfLOFF+ByGgh2gux6tbtE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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