SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39c5c0d55785884105ac2efd15d30bc0aeebe4a8cfe6fde5e6f927fe17aa3b13' 
  AND token = 'vjeI5DYEMQqi9cK3iYhUmNv0G17s9U0w1bgSxoFnlkc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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