SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b78442987ccc5777539629856aa439e2638e492cae72e92ce3803d2a8e52ef0' 
  AND token = 'J4hVSZxL7CAq01N7XTa0xsHiqFDJUTykyRQRklc1P1g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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