SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '395020bcdc7a6ef25f876392b1d0c9e8b791041dc8833ad1583f06c40f1da38f' 
  AND token = 'mYE5iKrIjfLxPKiCtHhfSBZuqHP7g4v71IfyHG56fqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}