SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a16d25a45699655cec21cd533372894332e2b7a3e9671d26a454c3390817a6a' 
  AND token = 'n6HuQnRN+5GzO82iSH0BhwmUrwUhRsqRN/KVURYYnbk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00133

JSON explain

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