SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4d937acc54c727d73dd0d2ea905f9014896945fddd2826d76f967060be95aa80' 
  AND token = 'YTuYS8baRCWVFyFXrhc+kM6Zm3XwoPlczignO8wmiSI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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