SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '46a7f9f34044d7b683d9b18ee20d9e0092f35e563fcf24921a665d1251a087d5' 
  AND token = 'p3MqpHz9HnhnI0cwyxCptJ1EZ3C7kHxBoBXXWC2PrKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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