SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b63229d9ff36d2bec828ff3bdb23d1dacac73eb1e649cb1a0d6683fe99203a4f' 
  AND token = 'OqQDzew5UR2cr07qcwpUd/SiHKCU6y3YaCyk+cLa4kg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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