SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d21f30be829f2fa098ca334fc5f939cb1c4c44cf345402d5f1ec4671e19c2f4' 
  AND token = 'irAgqQ94dIxBPkxNiNU45UlfuTUDC7Kxk7x9Bnmzbkk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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