SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6d031922decd22f1d8cffb488f1034b8b3573559d9aed126e6ba20f72681116' 
  AND token = 'U0hiaJKnex29OnVWyALHoYrs3OOCvoYS22jI6YjbVa4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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