SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40b87fb3312285e213ffcf202cb7b73e18ab97566ff4ab19363e5b10395aa652' 
  AND token = 'krLoMHjKTQQrie5MDbiBV0AZycnHBtMqjFTHRaiq7Aw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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