SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47f21f15c8f21a848ab8dea84506ab81bd1e8433f3c25bea9ba1b81434b17af6' 
  AND token = 'MNhKjbE5T8VS1RficX+tunP/7vOUgIBgMQsQzl5XS5E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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