SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c3390fc4a7c0d4f1685145d8f1b303eaaa5510178a4dadeb938488a8bc549910' 
  AND token = 'FX7tq2rRx6jG6fzNq6exImKws+Q+eWaccj/Bbnj8JKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00068

JSON explain

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