SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c6dbcac4b313a023937d440df6c07ae47a20745460ddd4be4d58f6f31781515' 
  AND token = 'fcrRS92fynqDCfxoYfae575uXeusuthYfkReRH8oSN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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