SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a0245df65d187f741cfbb0bc3afbd07fff154ddabf71e32a1991578071a800d' 
  AND token = '6oz1FmAe+xSUxakcvgW7dLvqDcFXjLJr78wExMgxdHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}