SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98a9cfe118d89504769cc1259ae031e004100921f8d4bc6dfa99b3b1f0a1d106' 
  AND token = 'zaZixABMdi7MgPaSxqkzE9wOo2/qQa+URcMh1PLk3P8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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