SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6da172547a1639639985f9cc4546f8606edfb971a74ed437f9ebb0aa694d4a50' 
  AND token = '4yPhOMQu2tjwRuBb6TwzlIKxTmTvF72lLLRPm8doHgA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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