SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3e9675160a453a58618c936c79dae9fe7e69576baec4901629239968e816009' 
  AND token = 'SB6MtDQI3+4EmE2iPY39IbVblefOObNVFR7TFKUlqUQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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