SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c3c28ba0c00fb2b2e4daa790947690b2bdf637d89d718c1c6b5e58f824dcee3' 
  AND token = '/vEhHvltJXAwaPJyWwjs59m+VAiJCJTj8BXoN9Vqaa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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