SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46840efc774fd5d9337b09df829333c9db7850da60fe303da6ca97b5431ed814' 
  AND token = 'ohc80wwTh0No+7q+HdzvRzSWrt4pPJn/gos84PCglHo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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