SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e14678708731b05b7de8b8a5afb9c41210e964ae6481547a9c5753b0e55142e3' 
  AND token = 'Nuh/PiAOqSmyE35w5AcZSWd5x6vqlgaS235T6uT9U7k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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