SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '909291aeaea4c49659880d824e092092ee2a6d635ed686c175d3d975cba21033' 
  AND token = 'HAeQ8rKqX5ZmSOMrB3sG/ZNvBuPTvFu9Ho+EjktMtN4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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