SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '788632943c617e9562bc7d5b5cb02fd8694efb4c9a90af585314467e66549009' 
  AND token = 'BOWFUuXlLecCWeeGluy9fi3XgnaClvdNsOXWZjZu40o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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