SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52720e4273c8c34d658002a6b7ce377838282def7ccacaa41355f684d9e648ee' 
  AND token = 'nvNgIgLYIABck54vNtbytPGwbkUHduexXIjZdY7C9jQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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