SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16959d091fff92c1350c90717b93275372d20a4d1d5d9994ec40d309498800d9' 
  AND token = 'jQs7qnu83JOi5VsgiWK4MwOrr+dHdYrCX48MnUxADIc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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