SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2df16aa7e0ff259b822626a5b68251c2a01107a0b30e994514c5bc9ac706b87a' 
  AND token = '5s//9GiURc6VtymQKmr5n+cKykHmaXNIFnN6XGMKQJw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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