SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82ce3ef7267dae109c073a4d2ebbd40accff7b50344763a7dc323f7be37c6e2f' 
  AND token = '9BxWLtIrCPs+uQVWAo6OhPaPvw+BU1iTM5U4XkdIpuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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