SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f06271c5430e5c021571f8f954c63fada40f09d67b4458092156222e17bed571' 
  AND token = 'LVzmWcwK2xp9zaFGidvFFc/mAI/DTmjVPzFeSXGOuFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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