SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '41ea0f21bb3c921cf687f6dce183866b30b8278765a5b0a29785606456d29935' 
  AND token = 'uYbDkDQZBRhcO8SB9TlaDz2MliqlL45GwsvDBmp6vg4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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