SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c0f32768a617a764ab96dca35309be3e9ada54250b93e39f76b9966d23addf5' 
  AND token = 't5+rPHQVvCZKk2L4lgqKFI5iQLRrRtBMYKHl8dzkUpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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