SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12fa122366d48b4e24e8d14a3c43966f11a092160c48d8348e38760978822cc9' 
  AND token = 'Of0FQSbl2xXwtxxVNfMsiZwESqv+UvrsqfkklXpJNk4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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