SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d87429ea20531b7cadc4fbf7dccb1f05b6c179620ed00ee334e26cfe1a18024' 
  AND token = '3fEIZeR/tmjwS7QWwF0P8/+bJ+ljviUiJmtKm2Z/gqA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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