SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7de6b9adcf055c4f0f86db128c7edd51f85069d5972e1e7a1b638065582210d5' 
  AND token = '9LoNvfvHzy2vl1bEU0Jm8d59F1hAeFeIqNfMtbKUrzw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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