SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3edd8ac83ee108eab09969a7d2c5602258e713902b7b2422b59d983fcac24960' 
  AND token = 'KBK52ccFPp0O0jrPRLIHadAZnbJHMPewWRUw8pBNvC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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