SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43941819e49bad90f1b286dddfd2f6274abedbdf33b7f1cb5f730da23accee8f' 
  AND token = 'PYMv/UQcwHiMJy6vxKW70IpcoKNg2usv8pUvsnOBcjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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