SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'acd53765eba24780b51a74e87983d748d59f814d06babc25b723f6e31f0f2888' 
  AND token = 'fY8evOG+54T5MqMc0ZdvNIcNcuRwPPCTchi+87ufsSM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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