SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b78e3f140fd9cbabeadda9009f28c2686eeddce44f0f79213f71f249bdd5659' 
  AND token = 'srbcXKUn1OOaDhiIlWFVIoz73Xyc4YQUFbGrIo1t6V0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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