SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '568d0b383ceec6bf1797143ca22f0a11a08b45e9fde5487a1c9ad8fbfe8485ff' 
  AND token = 'KYDVk7hAI/sX0SZB1T3HJQMwXZt1CZd6MA4vrF9vMtw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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