SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a103a56af01f514d612410f2f939cda47a560bb8b576adde3a733f887c4c622' 
  AND token = 'qYluYkF7ngVv0zkmED3uBRE9342SLdX5fmikd5ZC+/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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