SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1d4c1893755c1239fcf49999f54ea6849a24453dc24241e53d153f7815279861' 
  AND token = '5bqCcnSRlZdSRNxbO1YvSNrecqZkVsSYKAQJsEZiIDc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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