SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '546fc0cc79115e167980bbb32d14827346861ddf7b5c9a57fc69115ff135aff3' 
  AND token = 'QVpIyFvhkg0eSRnb1NcWeQnwFLCQkg4LsPQSCfZfKEM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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