SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6dcffe6f99f823ea9f1a418b9d930d1dd01fdff8bd3d6c2d58c8d9ae0a2fcbf6' 
  AND token = 'vluc4fHLGqWYhXdPeRVmZDBaKYwww6vo/28zZnuy35U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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