SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3482108911fcda426515c80e51256bb635ad5a954e91015b59cbf69485202a6' 
  AND token = 'aR7yyt9GxlzaUXY813ZEDuAZblacV79I0yHrKIU4kdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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