SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '79ec76235ec24dd4534a087adf57a4d31ae7fb97eb455001363641ddef10dcf7' 
  AND token = '/3dbjQGrVH/pDvhCwLmyS/gNpXBMudEaWeLsLbLM3GM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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