SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6afb4973e01330947a76bc27b19f96d8c6875e784f652d6e483683b64e2a29d' 
  AND token = 'Arim8GmpWOVZf5bmwz4kuTVm/9jbaohQpNQR8p1lC1Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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