SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc8670daf05e28750f74f7a579f820935b7ba42ee0195c40e39670f2af12c5a3' 
  AND token = 'TLkwohUc8HchXuXYxVicym2p2dcNg2+uWJK4MsEcZq4=' 
  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"
    }
  }
}