SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0121af2e605bcca6d4d8757852593cf73d99805b5cdf8dbf0690315c449550c5' 
  AND token = 'AdBZLsOOkPTQA11McrpzsyqU0NzEFyZeZeHoXFH9tPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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