SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e6b6c8c4cf0dd068d7ccd839e4691dd9def39c2740eee2368459d6a200307a8' 
  AND token = 'Upb4uDnkcZHylVdA4velb9cNwTn/jZ2nUUC5ra8q76I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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