SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '166b91cc9184e5ea188ac0a43a6e7682710259252ea05ca3c3cadc55ea349c3f' 
  AND token = 'dJ1JAyi7LOyVSBI+JctfqQsPiq6bbd0ea6e0gpe3HiU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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