SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a49f2118359354c32f9e92047cc683e3625e76a09937ac27edca1377ce3b32c4' 
  AND token = 'DlUMVpm/WcTEioCd9MkMZ6XmYsG+CGOqGkC7VbL/nW0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}