SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96c8281fc5163bedb663181a43c5c7e59abda48d224dbd04d2c0d1a28ac06974' 
  AND token = 'LMNMHurqo9UrxXpSW7ijdL46sAli0zFidNilWX489zE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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