SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c73a12501813019638118790648697e30973a7ebb329bac2bd7a621288a9cebe' 
  AND token = 'hKb6+/7rrCYumWJ5TNgIvzBCWPk41NLbjayLZuvZDS0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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