SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3275619dd68f51330e2e6d438a25c228d474b993944a1e73ffad7bd76bb4f6f7' 
  AND token = 'YKRbixYaQ/Db6fsmGWs3W//npBdVLs3sZWHvwppwaH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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