SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8d5d7b608d850dae7b98004494664b63c8ab837b81dc855d154abbd33bc072e' 
  AND token = 'AKUHp3gWdEo4d+19FWHpLQIXhDXVhrMaKXE6PFe+254=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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