SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd0b255b6041a4623ea1c9bc8cf5296c7716b4237c3b1205f4a750947931589d6' 
  AND token = '8a4DK7qLYDsRHmWOG6GuY3WBZ+2nQOYKfWzH3C8zVOE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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