SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '78c8f83726cd41a6ccaceace32fa4c8738752503de31265ad98ca01aca24efa5' 
  AND token = 'MoJKRD08kXkAidCOMsImbO5fF1rWscJuHvdlF6BjM9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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