SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d243b1e8c4a6b62dba878ad56551e82624f9f5fd06aa1e624c8c53e235773e4' 
  AND token = 'PZDhv9GOSv7uyT0+ATw3bFjpSxDiXbgfSIyzrsXZlRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00066

JSON explain

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