SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83c8c9c9da6fa7b1ec89cf8c9140f22558d9fda86bade335145f69ccd844a729' 
  AND token = 'ihmj+VWpEYS/0W52Wm/zKFJXNOVZnTlaF/lkJUQ7pb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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