SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '508d6e308cd33a182288091fbbe371d1635c07c644008d8f9caf1018c99104c7' 
  AND token = 'AI7gMWwxD6sTNarITjOG4F1CyrTYDx/aIZBh6L9Qpeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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