SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a6ad26aae370e98f15e8af1a41d454c824fd94f4d810cf48a150699ed91eab8' 
  AND token = 'kXXBpdWe22aXL6XMKJ6pVVuU2nyClhmMKbKhBwRMk7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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