SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68bfd534964025e107339b3b7eedbc833293fec5602501d36fe08cfe77e98c69' 
  AND token = 'LRTF4hcmjXMr2IaoKR39LVpC31TGy/nK4JkRIlKFjWo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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