SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30c9552642d2f6d72b976408cd9e8e6868a559f1eb8664f5568b6b138314fc5b' 
  AND token = 'B9NiAMaiQB+/nP2afEstxCQjSPf8fmWZ0vTxIDxDjuc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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