SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c992343ba381711074d974dddbde92d0a3f84392c5ad65dea6332d6492a34dae' 
  AND token = 'P+SZxNmZNT8b/6yBInbk9A2G42MfIExkxywEUGiJlVs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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