SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e83e76a7332a722754e2cbc6eef3e044a6d3e40d915bc6117eebdfbfd716dbf' 
  AND token = 'r/0TQ995zclP66mTiHajty8ltZXLxVTOGxfXMPHR0Gs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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