SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '495d9b9619c9fa960c9146d358e5fa20c0f10dfdef562898477deb0b09d0f410' 
  AND token = 'EjvWBkG/WDKTOmH78CXUgzXT8AqmPQB0NYlOmYnXKhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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