SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '268692e98f080b454ed3f68260beb5323e1f5e632d9fef283735a666cdc4f22c' 
  AND token = 'h4xke/rFx1mSGfwNAtEEpzHWJ63vsE3zqoXCofhDH5A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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