SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a88ac99ab9181ae8742d20ec4ac3efcd0e7a851cd7edc80667e92eb8c56ebfa' 
  AND token = 'QK9BvWhR70uXc11XUSpWp9zDDJZ5QaWGUg7EziSuGTM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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