SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6e445e0ee65cb509046b1f91d732471f148a933148d933a857d79100f0b09a2' 
  AND token = 'nwUHFU2WtYEjnlk/Ltm4awOTwqrFYt1zWsvtF0nUExs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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