SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9b7aade853c5811203cfd6ca928a5fea17a24e0cf6942c4d10efc8479f98216' 
  AND token = 'W9w3sPsxV8DjdzC7xDfZPoLG6NvW2+4Yb/OMKR89md0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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