SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4e5735c220cad94eff0f345f8e007541e3e4575a23ff3c230fed21bdebeb886' 
  AND token = 'aX0mC7v4UF/jgfRZj3YtEH4K7zG/1gywBK6F9nJaGto=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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