SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71d2a6d140f6ba2e76beed51238434730b9f5894b0f59c1ed98202eae92f8fe4' 
  AND token = '9dQ8Nfk+VIxej/ggJVOcGkO+/+g6wTnajL1GZ01tiRA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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