SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '852702f83f44e1d1f41d3c28a672e9e7a43a0bc5533dc80408ddcbce1699491b' 
  AND token = 'WLhuPx6CrnWg4694VVgdbLiHQ1XBgkYunifIP5tUHv8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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