SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8739a144e337e68f450fc07f4615e42bce27f4fef41a948aff4909c9081c7b60' 
  AND token = '7WgbsD08MkQG0cl294ZQMXV8MaD3oLfjfrjlXvavoCg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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