SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '43b76b568048f9089aa044df1aa4046398b108de0523f309e1f834ad389c32a7' 
  AND token = 'bvUMP/6LVN5rIvjc6m5lLv4yHS8L3B+hu8jmPliJKNk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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