SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af1d6ec8a8303328c132a4f2bd490bf09afa74f79094687a40d5dafbc9234881' 
  AND token = 'fTVjoGwtM5B8N3n4khcbxrClsVKv/+CHC0K0AUaDRIA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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