SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f642b19ee50cd5e544750b6fc43a0c3899d393174dca2da820e777eff5cdd185' 
  AND token = '2zT7zgRlM9qXBpl9oXZJ8v9v+L8/AZpq+bXZxPuP71c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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