SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '276405d9dda873a9e209e8f4ac744475582cbabed9d50401a4f35b7ed746a326' 
  AND token = 'cYpRmzbMBZOEYUd+Ik2zscTX/PPu5xiTfmOZnOZZYpk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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