SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f791bae1a5ec38081757b9c01d41c89ec55db154f867adc26ff7b32edf833d23' 
  AND token = 'FYk9/iuvlhJfv8uSSCagoUHWA20PSOFj82ofpEtyb64=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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